CVE-2026-23943

{"dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": {"cveId": "CVE-2026-23943", "assignerOrgId": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db", "state": "PUBLISHED", "assignerShortName": "EEF", "dateReserved": "2026-01-19T14:23:14.343Z", "datePublished": "2026-03-13T09:11:57.794Z", "dateUpdated": "2026-11-11T19:44:14.524Z"}, "containers": {"cna": {"affected": [{"cpes": ["cpe:2.3:a:erlang:erlang\\/otp:*:*:*:*:*:*:*:*"], "defaultStatus": "unaffected", "modules": ["ssh_transport"], "packageName": "otp", "packageURL": "pkg:software-id/erlang.org/otp", "product": "OTP", "programFiles": ["lib/ssh/src/ssh_transport.erl"], "programRoutines": [{"name": "ssh_transport:decompress/2"}, {"name": "ssh_transport:handle_packet_part/4"}], "vendor": "Erlang", "versions": [{"changes": [{"at": "26.2.5.18", "status": "unaffected"}, {"at": "27.3.4.9", "status": "unaffected"}, {"at": "28.4.1", "status": "unaffected"}], "lessThan": "*", "status": "affected", "version": "17.0", "versionType": "otp"}]}, {"cpes": ["cpe:2.3:a:erlang:erlang\\/otp:*:*:*:*:*:*:*:*"], "defaultStatus": "unaffected", "modules": ["ssh_transport"], "packageName": "ssh", "packageURL": "pkg:otp/ssh?repository_url=https:%2F%2Fgithub.com%2Ferlang%2Fotp&vcs_url=git%2Bhttps:%2F%2Fgithub.com%2Ferlang%2Fotp.git", "product": "OTP", "programFiles": ["src/ssh_transport.erl"], "programRoutines": [{"name": "ssh_transport:decompress/2"}, {"name": "ssh_transport:handle_packet_part/4"}], "repo": "https://github.com/erlang/otp", "vendor": "Erlang", "versions": [{"changes": [{"at": "5.1.4.14", "status": "unaffected"}, {"at": "5.2.11.6", "status": "unaffected"}, {"at": "5.5.1", "status": "unaffected"}], "lessThan": "*", "status": "affected", "version": "3.0.1", "versionType": "otp"}]}, {"collectionURL": "https://github.com", "cpes": ["cpe:2.3:a:erlang:erlang\\/otp:*:*:*:*:*:*:*:*"], "defaultStatus": "unaffected", "modules": ["ssh_transport"], "packageName": "erlang/otp", "packageURL": "pkg:github/erlang/otp", "product": "OTP", "programFiles": ["lib/ssh/src/ssh_transport.erl"], "programRoutines": [{"name": "ssh_transport:decompress/2"}, {"name": "ssh_transport:handle_packet_part/4"}], "repo": "https://github.com/erlang/otp", "vendor": "Erlang", "versions": [{"changes": [{"at": "0c1c04b191f6ab940e8fcfabce39eb5a8a6440a4", "status": "unaffected"}, {"at": "93073c3bd338c60cd2bae715ce6a1d4ffc1a8fd3", "status": "unaffected"}, {"at": "43a87b949bdff12d629a8c34146711d9da93b1b1", "status": "unaffected"}], "lessThan": "*", "status": "affected", "version": "07b8f441ca711f9812fad9e9115bab3c3aa92f79", "versionType": "git"}]}], "configurations": [{"lang": "en", "supportingMedia": [{"base64": false, "type": "text/html", "value": "<p>The SSH server or client must advertise <code>zlib</code> or <code>zlib@openssh.com</code> compression. Both are enabled by default. With <code>zlib</code>, the attack is pre-authentication; with <code>zlib@openssh.com</code>, authentication is required first.</p>"}, {"base64": false, "type": "text/markdown", "value": "The SSH server or client must advertise `zlib` or `zlib@openssh.com` compression. Both are enabled by default. With `zlib`, the attack is pre-authentication; with `zlib@openssh.com`, authentication is required first."}], "value": "The SSH server or client must advertise zlib or zlib@openssh.com compression. Both are enabled by default. With zlib, the attack is pre-authentication; with zlib@openssh.com, authentication is required first."}], "cpeApplicability": [{"nodes": [{"cpeMatch": [{"criteria": "cpe:2.3:a:erlang:erlang\\/otp:*:*:*:*:*:*:*:*", "versionEndExcluding": "26.2.5.18", "versionStartIncluding": "17.0", "vulnerable": true}, {"criteria": "cpe:2.3:a:erlang:erlang\\/otp:*:*:*:*:*:*:*:*", "versionEndExcluding": "27.3.4.9", "versionStartIncluding": "27.0", "vulnerable": true}, {"criteria": "cpe:2.3:a:erlang:erlang\\/otp:*:*:*:*:*:*:*:*", "versionEndExcluding": "28.4.1", "versionStartIncluding": "28.0", "vulnerable": true}], "negate": false, "operator": "OR"}], "operator": "AND"}], "credits": [{"lang": "en", "type": "finder", "value": "Igor Morgenstern / Aisle Research"}, {"lang": "en", "type": "remediation developer", "value": "Micha\u0142 W\u0105sowski"}, {"lang": "en", "type": "remediation reviewer", "value": "Jakub Witczak"}], "datePublic": "2026-03-13T09:11:57.000Z", "descriptions": [{"lang": "en", "supportingMedia": [{"base64": false, "type": "text/html", "value": "<p>Improper Handling of Highly Compressed Data (Compression Bomb) vulnerability in Erlang OTP ssh (ssh_transport modules) allows Denial of Service via Resource Depletion.</p>\n<p>The SSH transport layer advertises legacy zlib compression by default and inflates attacker-controlled payloads pre-authentication without any size limit, enabling reliable memory exhaustion DoS.</p>\n<p>Two compression algorithms are affected:</p>\n<ul>\n<li><strong><code>zlib</code>:</strong> Activates immediately after key exchange, enabling unauthenticated attacks</li>\n<li><strong><code>zlib@openssh.com</code>:</strong> Activates post-authentication, enabling authenticated attacks</li>\n</ul>\n<p>Each SSH packet can decompress ~255 MB from 256 KB of wire data (1029:1 amplification ratio). Multiple packets can rapidly exhaust available memory, causing OOM kills in memory-constrained environments.</p>\n<p>This vulnerability is associated with program files <code>lib/ssh/src/ssh_transport.erl</code> and program routines <code>ssh_transport:decompress/2</code>, <code>ssh_transport:handle_packet_part/4</code>.</p>\n<p>This issue affects OTP from OTP&nbsp;17.0 before OTP&nbsp;26.2.5.18, OTP&nbsp;27.3.4.9, and OTP&nbsp;28.4.1, corresponding to ssh from 3.0.1 before 5.1.4.14, 5.2.11.6, and 5.5.1.</p>"}, {"base64": false, "type": "text/markdown", "value": "Improper Handling of Highly Compressed Data (Compression Bomb) vulnerability in Erlang OTP ssh (ssh_transport modules) allows Denial of Service via Resource Depletion.\n\nThe SSH transport layer advertises legacy zlib compression by default and inflates attacker-controlled payloads pre-authentication without any size limit, enabling reliable memory exhaustion DoS.\n\nTwo compression algorithms are affected:\n\n* **`zlib`:** Activates immediately after key exchange, enabling unauthenticated attacks\n* **`zlib@openssh.com`:** Activates post-authentication, enabling authenticated attacks\n\nEach SSH packet can decompress ~255 MB from 256 KB of wire data (1029:1 amplification ratio). Multiple packets can rapidly exhaust available memory, causing OOM kills in memory-constrained environments.\n\nThis vulnerability is associated with program files `lib/ssh/src/ssh_transport.erl` and program routines `ssh_transport:decompress/2`, `ssh_transport:handle_packet_part/4`.\n\nThis issue affects OTP from OTP\u00a017.0 before OTP\u00a026.2.5.18, OTP\u00a027.3.4.9, and OTP\u00a028.4.1, corresponding to ssh from 3.0.1 before 5.1.4.14, 5.2.11.6, and 5.5.1."}], "value": "Improper Handling of Highly Compressed Data (Compression Bomb) vulnerability in Erlang OTP ssh (ssh_transport modules) allows Denial of Service via Resource Depletion.\n\nThe SSH transport layer advertises legacy zlib compression by default and inflates attacker-controlled payloads pre-authentication without any size limit, enabling reliable memory exhaustion DoS.\n\nTwo compression algorithms are affected:\n\n* zlib: Activates immediately after key exchange, enabling unauthenticated attacks\n* zlib@openssh.com: Activates post-authentication, enabling authenticated attacks\n\nEach SSH packet can decompress ~255 MB from 256 KB of wire data (1029:1 amplification ratio). Multiple packets can rapidly exhaust available memory, causing OOM kills in memory-constrained environments.\n\nThis vulnerability is associated with program files lib/ssh/src/ssh_transport.erl and program routines ssh_transport:decompress/2, ssh_transport:handle_packet_part/4.\n\nThis issue affects OTP from OTP\u00a017.0 before OTP\u00a026.2.5.18, OTP\u00a027.3.4.9, and OTP\u00a028.4.1, corresponding to ssh from 3.0.1 before 5.1.4.14, 5.2.11.6, and 5.5.1."}], "impacts": [{"capecId": "CAPEC-130", "descriptions": [{"lang": "en", "value": "CAPEC-130 Excessive Allocation"}]}, {"capecId": "CAPEC-490", "descriptions": [{"lang": "en", "value": "CAPEC-490 Amplification"}]}], "metrics": [{"cvssV4_0": {"Automatable": "NOT_DEFINED", "Recovery": "NOT_DEFINED", "Safety": "NOT_DEFINED", "attackComplexity": "LOW", "attackRequirements": "NONE", "attackVector": "NETWORK", "baseScore": 6.9, "baseSeverity": "MEDIUM", "privilegesRequired": "NONE", "providerUrgency": "NOT_DEFINED", "subAvailabilityImpact": "NONE", "subConfidentialityImpact": "NONE", "subIntegrityImpact": "NONE", "userInteraction": "NONE", "valueDensity": "NOT_DEFINED", "vectorString": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N", "version": "4.0", "vulnAvailabilityImpact": "LOW", "vulnConfidentialityImpact": "NONE", "vulnIntegrityImpact": "NONE", "vulnerabilityResponseEffort": "NOT_DEFINED"}, "format": "CVSS", "scenarios": [{"lang": "en", "value": "GENERAL"}]}], "problemTypes": [{"descriptions": [{"cweId": "CWE-409", "description": "CWE-409 Improper Handling of Highly Compressed Data (Data Amplification)", "lang": "en", "type": "CWE"}]}], "providerMetadata": {"orgId": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db", "shortName": "EEF", "dateUpdated": "2026-11-11T19:44:14.524Z"}, "references": [{"name": "Pre-auth SSH DoS via unbounded zlib inflate", "tags": ["vendor-advisory", "related"], "url": "https://github.com/erlang/otp/security/advisories/GHSA-c836-qprm-jw9r"}, {"name": "EEF CNA record for CVE-2026-23943", "tags": ["related"], "url": "https://cna.erlef.org/cves/CVE-2026-23943.html"}, {"name": "OSV record EEF-CVE-2026-23943", "tags": ["related"], "url": "https://osv.dev/vulnerability/EEF-CVE-2026-23943"}, {"name": "Erlang/OTP version ordering", "tags": ["x_version-scheme"], "url": "https://www.erlang.org/doc/system/versions.html#order-of-versions"}, {"name": "Introducing commit 07b8f44 in erlang/otp", "tags": ["related"], "url": "https://github.com/erlang/otp/commit/07b8f441ca711f9812fad9e9115bab3c3aa92f79"}, {"name": "Fix commit 0c1c04b in erlang/otp", "tags": ["patch"], "url": "https://github.com/erlang/otp/commit/0c1c04b191f6ab940e8fcfabce39eb5a8a6440a4"}, {"name": "Fix commit 93073c3 in erlang/otp", "tags": ["patch"], "url": "https://github.com/erlang/otp/commit/93073c3bd338c60cd2bae715ce6a1d4ffc1a8fd3"}, {"name": "Fix commit 43a87b9 in erlang/otp", "tags": ["patch"], "url": "https://github.com/erlang/otp/commit/43a87b949bdff12d629a8c34146711d9da93b1b1"}], "source": {"discovery": "EXTERNAL"}, "title": "Pre-auth SSH DoS via unbounded zlib inflate", "workarounds": [{"lang": "en", "supportingMedia": [{"base64": false, "type": "text/html", "value": "<p><strong>Best workaround - Disable all compression:</strong></p>\n<pre><code class=\"language-erlang\">{preferred_algorithms, [{compression, ['none']}]}\n</code></pre>\n<p><strong>Alternative mitigations (less secure):</strong></p>\n<ul>\n<li>\n<p>Disable only pre-auth zlib compression (authenticated users can still exploit via <code>zlib@openssh.com</code>):</p>\n<pre><code class=\"language-erlang\">{modify_algorithms, [{rm, [{compression, ['zlib']}]}]}\n</code></pre>\n</li>\n<li>\n<p>Limit concurrent sessions (reduces attack surface but does not prevent exploitation):</p>\n<pre><code class=\"language-erlang\">{max_sessions, N} % Cap total concurrent sessions (default is infinity)\n</code></pre>\n</li>\n</ul>"}, {"base64": false, "type": "text/markdown", "value": "**Best workaround - Disable all compression:**\n\n```erlang\n{preferred_algorithms, [{compression, ['none']}]}\n```\n\n**Alternative mitigations (less secure):**\n\n* Disable only pre-auth zlib compression (authenticated users can still exploit via `zlib@openssh.com`):\n\n ```erlang\n {modify_algorithms, [{rm, [{compression, ['zlib']}]}]}\n ```\n\n* Limit concurrent sessions (reduces attack surface but does not prevent exploitation):\n\n ```erlang\n {max_sessions, N} % Cap total concurrent sessions (default is infinity)\n ```"}], "value": "Best workaround - Disable all compression:\n\n{preferred_algorithms, [{compression, ['none']}]}\n\nAlternative mitigations (less secure):\n\n* Disable only pre-auth zlib compression (authenticated users can still exploit via zlib@openssh.com):\n{modify_algorithms, [{rm, [{compression, ['zlib']}]}]}\n* Limit concurrent sessions (reduces attack surface but does not prevent exploitation):\n{max_sessions, N} % Cap total concurrent sessions (default is infinity)"}]}, "adp": [{"metrics": [{"other": {"type": "ssvc", "content": {"timestamp": "2026-03-13T16:01:40.898658Z", "id": "CVE-2026-23943", "options": [{"Exploitation": "none"}, {"Automatable": "yes"}, {"Technical Impact": "partial"}], "role": "CISA Coordinator", "version": "2.0.3"}}}], "title": "CISA ADP Vulnrichment", "providerMetadata": {"orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "shortName": "CISA-ADP", "dateUpdated": "2026-03-13T16:01:48.609Z"}}]}}

{"dataType": "CVE_RECORD", "containers": {"adp": [{"title": "CISA ADP Vulnrichment", "metrics": [{"other": {"type": "ssvc", "content": {"id": "CVE-2026-23943", "role": "CISA Coordinator", "options": [{"Exploitation": "none"}, {"Automatable": "yes"}, {"Technical Impact": "partial"}], "version": "2.0.3", "timestamp": "2026-03-13T16:01:40.898658Z"}}}], "providerMetadata": {"orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "shortName": "CISA-ADP", "dateUpdated": "2026-03-13T16:01:44.722Z"}}], "cna": {"title": "Pre-auth SSH DoS via unbounded zlib inflate", "source": {"discovery": "EXTERNAL"}, "credits": [{"lang": "en", "type": "finder", "value": "Igor Morgenstern / Aisle Research"}, {"lang": "en", "type": "remediation developer", "value": "Micha\u0142 W\u0105sowski"}, {"lang": "en", "type": "remediation reviewer", "value": "Jakub Witczak"}], "impacts": [{"capecId": "CAPEC-130", "descriptions": [{"lang": "en", "value": "CAPEC-130 Excessive Allocation"}]}, {"capecId": "CAPEC-490", "descriptions": [{"lang": "en", "value": "CAPEC-490 Amplification"}]}], "metrics": [{"format": "CVSS", "cvssV4_0": {"Safety": "NOT_DEFINED", "version": "4.0", "Recovery": "NOT_DEFINED", "baseScore": 6.9, "Automatable": "NOT_DEFINED", "attackVector": "NETWORK", "baseSeverity": "MEDIUM", "valueDensity": "NOT_DEFINED", "vectorString": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N", "providerUrgency": "NOT_DEFINED", "userInteraction": "NONE", "attackComplexity": "LOW", "attackRequirements": "NONE", "privilegesRequired": "NONE", "subIntegrityImpact": "NONE", "vulnIntegrityImpact": "NONE", "subAvailabilityImpact": "NONE", "vulnAvailabilityImpact": "LOW", "subConfidentialityImpact": "NONE", "vulnConfidentialityImpact": "NONE", "vulnerabilityResponseEffort": "NOT_DEFINED"}, "scenarios": [{"lang": "en", "value": "GENERAL"}]}], "affected": [{"cpes": ["cpe:2.3:a:erlang:erlang\\/otp:*:*:*:*:*:*:*:*"], "vendor": "Erlang", "modules": ["ssh_transport"], "product": "OTP", "versions": [{"status": "affected", "changes": [{"at": "26.2.5.18", "status": "unaffected"}, {"at": "27.3.4.9", "status": "unaffected"}, {"at": "28.4.1", "status": "unaffected"}], "version": "17.0", "lessThan": "*", "versionType": "otp"}], "packageURL": "pkg:software-id/erlang.org/otp", "packageName": "otp", "programFiles": ["lib/ssh/src/ssh_transport.erl"], "defaultStatus": "unaffected", "programRoutines": [{"name": "ssh_transport:decompress/2"}, {"name": "ssh_transport:handle_packet_part/4"}]}, {"cpes": ["cpe:2.3:a:erlang:erlang\\/otp:*:*:*:*:*:*:*:*"], "repo": "https://github.com/erlang/otp", "vendor": "Erlang", "modules": ["ssh_transport"], "product": "OTP", "versions": [{"status": "affected", "changes": [{"at": "5.1.4.14", "status": "unaffected"}, {"at": "5.2.11.6", "status": "unaffected"}, {"at": "5.5.1", "status": "unaffected"}], "version": "3.0.1", "lessThan": "*", "versionType": "otp"}], "packageURL": "pkg:otp/ssh?repository_url=https:%2F%2Fgithub.com%2Ferlang%2Fotp&vcs_url=git%2Bhttps:%2F%2Fgithub.com%2Ferlang%2Fotp.git", "packageName": "ssh", "programFiles": ["src/ssh_transport.erl"], "defaultStatus": "unaffected", "programRoutines": [{"name": "ssh_transport:decompress/2"}, {"name": "ssh_transport:handle_packet_part/4"}]}, {"cpes": ["cpe:2.3:a:erlang:erlang\\/otp:*:*:*:*:*:*:*:*"], "repo": "https://github.com/erlang/otp", "vendor": "Erlang", "modules": ["ssh_transport"], "product": "OTP", "versions": [{"status": "affected", "changes": [{"at": "0c1c04b191f6ab940e8fcfabce39eb5a8a6440a4", "status": "unaffected"}, {"at": "93073c3bd338c60cd2bae715ce6a1d4ffc1a8fd3", "status": "unaffected"}, {"at": "43a87b949bdff12d629a8c34146711d9da93b1b1", "status": "unaffected"}], "version": "07b8f441ca711f9812fad9e9115bab3c3aa92f79", "lessThan": "*", "versionType": "git"}], "packageURL": "pkg:github/erlang/otp", "packageName": "erlang/otp", "programFiles": ["lib/ssh/src/ssh_transport.erl"], "collectionURL": "https://github.com", "defaultStatus": "unaffected", "programRoutines": [{"name": "ssh_transport:decompress/2"}, {"name": "ssh_transport:handle_packet_part/4"}]}], "datePublic": "2026-03-13T09:11:57.000Z", "references": [{"url": "https://github.com/erlang/otp/security/advisories/GHSA-c836-qprm-jw9r", "name": "Pre-auth SSH DoS via unbounded zlib inflate", "tags": ["vendor-advisory", "related"]}, {"url": "https://cna.erlef.org/cves/CVE-2026-23943.html", "name": "EEF CNA record for CVE-2026-23943", "tags": ["related"]}, {"url": "https://osv.dev/vulnerability/EEF-CVE-2026-23943", "name": "OSV record EEF-CVE-2026-23943", "tags": ["related"]}, {"url": "https://www.erlang.org/doc/system/versions.html#order-of-versions", "name": "Erlang/OTP version ordering", "tags": ["x_version-scheme"]}, {"url": "https://github.com/erlang/otp/commit/07b8f441ca711f9812fad9e9115bab3c3aa92f79", "name": "Introducing commit 07b8f44 in erlang/otp", "tags": ["related"]}, {"url": "https://github.com/erlang/otp/commit/0c1c04b191f6ab940e8fcfabce39eb5a8a6440a4", "name": "Fix commit 0c1c04b in erlang/otp", "tags": ["patch"]}, {"url": "https://github.com/erlang/otp/commit/93073c3bd338c60cd2bae715ce6a1d4ffc1a8fd3", "name": "Fix commit 93073c3 in erlang/otp", "tags": ["patch"]}, {"url": "https://github.com/erlang/otp/commit/43a87b949bdff12d629a8c34146711d9da93b1b1", "name": "Fix commit 43a87b9 in erlang/otp", "tags": ["patch"]}], "workarounds": [{"lang": "en", "value": "Best workaround - Disable all compression:\n\n{preferred_algorithms, [{compression, ['none']}]}\n\nAlternative mitigations (less secure):\n\n* Disable only pre-auth zlib compression (authenticated users can still exploit via zlib@openssh.com):\n{modify_algorithms, [{rm, [{compression, ['zlib']}]}]}\n* Limit concurrent sessions (reduces attack surface but does not prevent exploitation):\n{max_sessions, N} % Cap total concurrent sessions (default is infinity)", "supportingMedia": [{"type": "text/html", "value": "<p><strong>Best workaround - Disable all compression:</strong></p>\n<pre><code class=\"language-erlang\">{preferred_algorithms, [{compression, ['none']}]}\n</code></pre>\n<p><strong>Alternative mitigations (less secure):</strong></p>\n<ul>\n<li>\n<p>Disable only pre-auth zlib compression (authenticated users can still exploit via <code>zlib@openssh.com</code>):</p>\n<pre><code class=\"language-erlang\">{modify_algorithms, [{rm, [{compression, ['zlib']}]}]}\n</code></pre>\n</li>\n<li>\n<p>Limit concurrent sessions (reduces attack surface but does not prevent exploitation):</p>\n<pre><code class=\"language-erlang\">{max_sessions, N} % Cap total concurrent sessions (default is infinity)\n</code></pre>\n</li>\n</ul>", "base64": false}, {"type": "text/markdown", "value": "**Best workaround - Disable all compression:**\n\n```erlang\n{preferred_algorithms, [{compression, ['none']}]}\n```\n\n**Alternative mitigations (less secure):**\n\n* Disable only pre-auth zlib compression (authenticated users can still exploit via `zlib@openssh.com`):\n\n ```erlang\n {modify_algorithms, [{rm, [{compression, ['zlib']}]}]}\n ```\n\n* Limit concurrent sessions (reduces attack surface but does not prevent exploitation):\n\n ```erlang\n {max_sessions, N} % Cap total concurrent sessions (default is infinity)\n ```", "base64": false}]}], "descriptions": [{"lang": "en", "value": "Improper Handling of Highly Compressed Data (Compression Bomb) vulnerability in Erlang OTP ssh (ssh_transport modules) allows Denial of Service via Resource Depletion.\n\nThe SSH transport layer advertises legacy zlib compression by default and inflates attacker-controlled payloads pre-authentication without any size limit, enabling reliable memory exhaustion DoS.\n\nTwo compression algorithms are affected:\n\n* zlib: Activates immediately after key exchange, enabling unauthenticated attacks\n* zlib@openssh.com: Activates post-authentication, enabling authenticated attacks\n\nEach SSH packet can decompress ~255 MB from 256 KB of wire data (1029:1 amplification ratio). Multiple packets can rapidly exhaust available memory, causing OOM kills in memory-constrained environments.\n\nThis vulnerability is associated with program files lib/ssh/src/ssh_transport.erl and program routines ssh_transport:decompress/2, ssh_transport:handle_packet_part/4.\n\nThis issue affects OTP from OTP\u00a017.0 before OTP\u00a026.2.5.18, OTP\u00a027.3.4.9, and OTP\u00a028.4.1, corresponding to ssh from 3.0.1 before 5.1.4.14, 5.2.11.6, and 5.5.1.", "supportingMedia": [{"type": "text/html", "value": "<p>Improper Handling of Highly Compressed Data (Compression Bomb) vulnerability in Erlang OTP ssh (ssh_transport modules) allows Denial of Service via Resource Depletion.</p>\n<p>The SSH transport layer advertises legacy zlib compression by default and inflates attacker-controlled payloads pre-authentication without any size limit, enabling reliable memory exhaustion DoS.</p>\n<p>Two compression algorithms are affected:</p>\n<ul>\n<li><strong><code>zlib</code>:</strong> Activates immediately after key exchange, enabling unauthenticated attacks</li>\n<li><strong><code>zlib@openssh.com</code>:</strong> Activates post-authentication, enabling authenticated attacks</li>\n</ul>\n<p>Each SSH packet can decompress ~255 MB from 256 KB of wire data (1029:1 amplification ratio). Multiple packets can rapidly exhaust available memory, causing OOM kills in memory-constrained environments.</p>\n<p>This vulnerability is associated with program files <code>lib/ssh/src/ssh_transport.erl</code> and program routines <code>ssh_transport:decompress/2</code>, <code>ssh_transport:handle_packet_part/4</code>.</p>\n<p>This issue affects OTP from OTP&nbsp;17.0 before OTP&nbsp;26.2.5.18, OTP&nbsp;27.3.4.9, and OTP&nbsp;28.4.1, corresponding to ssh from 3.0.1 before 5.1.4.14, 5.2.11.6, and 5.5.1.</p>", "base64": false}, {"type": "text/markdown", "value": "Improper Handling of Highly Compressed Data (Compression Bomb) vulnerability in Erlang OTP ssh (ssh_transport modules) allows Denial of Service via Resource Depletion.\n\nThe SSH transport layer advertises legacy zlib compression by default and inflates attacker-controlled payloads pre-authentication without any size limit, enabling reliable memory exhaustion DoS.\n\nTwo compression algorithms are affected:\n\n* **`zlib`:** Activates immediately after key exchange, enabling unauthenticated attacks\n* **`zlib@openssh.com`:** Activates post-authentication, enabling authenticated attacks\n\nEach SSH packet can decompress ~255 MB from 256 KB of wire data (1029:1 amplification ratio). Multiple packets can rapidly exhaust available memory, causing OOM kills in memory-constrained environments.\n\nThis vulnerability is associated with program files `lib/ssh/src/ssh_transport.erl` and program routines `ssh_transport:decompress/2`, `ssh_transport:handle_packet_part/4`.\n\nThis issue affects OTP from OTP\u00a017.0 before OTP\u00a026.2.5.18, OTP\u00a027.3.4.9, and OTP\u00a028.4.1, corresponding to ssh from 3.0.1 before 5.1.4.14, 5.2.11.6, and 5.5.1.", "base64": false}]}], "problemTypes": [{"descriptions": [{"lang": "en", "type": "CWE", "cweId": "CWE-409", "description": "CWE-409 Improper Handling of Highly Compressed Data (Data Amplification)"}]}], "configurations": [{"lang": "en", "value": "The SSH server or client must advertise zlib or zlib@openssh.com compression. Both are enabled by default. With zlib, the attack is pre-authentication; with zlib@openssh.com, authentication is required first.", "supportingMedia": [{"type": "text/html", "value": "<p>The SSH server or client must advertise <code>zlib</code> or <code>zlib@openssh.com</code> compression. Both are enabled by default. With <code>zlib</code>, the attack is pre-authentication; with <code>zlib@openssh.com</code>, authentication is required first.</p>", "base64": false}, {"type": "text/markdown", "value": "The SSH server or client must advertise `zlib` or `zlib@openssh.com` compression. Both are enabled by default. With `zlib`, the attack is pre-authentication; with `zlib@openssh.com`, authentication is required first.", "base64": false}]}], "cpeApplicability": [{"nodes": [{"negate": false, "cpeMatch": [{"criteria": "cpe:2.3:a:erlang:erlang\\/otp:*:*:*:*:*:*:*:*", "vulnerable": true, "versionEndExcluding": "26.2.5.18", "versionStartIncluding": "17.0"}, {"criteria": "cpe:2.3:a:erlang:erlang\\/otp:*:*:*:*:*:*:*:*", "vulnerable": true, "versionEndExcluding": "27.3.4.9", "versionStartIncluding": "27.0"}, {"criteria": "cpe:2.3:a:erlang:erlang\\/otp:*:*:*:*:*:*:*:*", "vulnerable": true, "versionEndExcluding": "28.4.1", "versionStartIncluding": "28.0"}], "operator": "OR"}], "operator": "AND"}], "providerMetadata": {"orgId": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db", "shortName": "EEF", "dateUpdated": "2026-11-11T19:44:14.524Z"}}}, "cveMetadata": {"cveId": "CVE-2026-23943", "state": "PUBLISHED", "dateUpdated": "2026-11-11T19:44:14.524Z", "dateReserved": "2026-01-19T14:23:14.343Z", "assignerOrgId": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db", "datePublished": "2026-03-13T09:11:57.794Z", "assignerShortName": "EEF"}, "dataVersion": "5.2"}

{"affected": [{"affectedData": [{"cpes": ["cpe:2.3:a:erlang:erlang\\/otp:*:*:*:*:*:*:*:*"], "defaultStatus": "unaffected", "modules": ["ssh_transport"], "packageName": "otp", "packageURL": "pkg:software-id/erlang.org/otp", "product": "OTP", "programFiles": ["lib/ssh/src/ssh_transport.erl"], "programRoutines": [{"name": "ssh_transport:decompress/2"}, {"name": "ssh_transport:handle_packet_part/4"}], "vendor": "Erlang", "versions": [{"changes": [{"at": "26.2.5.18", "status": "unaffected"}, {"at": "27.3.4.9", "status": "unaffected"}, {"at": "28.4.1", "status": "unaffected"}], "lessThan": "*", "status": "affected", "version": "17.0", "versionType": "otp"}]}, {"cpes": ["cpe:2.3:a:erlang:erlang\\/otp:*:*:*:*:*:*:*:*"], "defaultStatus": "unaffected", "modules": ["ssh_transport"], "packageName": "ssh", "packageURL": "pkg:otp/ssh?repository_url=https:%2F%2Fgithub.com%2Ferlang%2Fotp&vcs_url=git%2Bhttps:%2F%2Fgithub.com%2Ferlang%2Fotp.git", "product": "OTP", "programFiles": ["src/ssh_transport.erl"], "programRoutines": [{"name": "ssh_transport:decompress/2"}, {"name": "ssh_transport:handle_packet_part/4"}], "repo": "https://github.com/erlang/otp", "vendor": "Erlang", "versions": [{"changes": [{"at": "5.1.4.14", "status": "unaffected"}, {"at": "5.2.11.6", "status": "unaffected"}, {"at": "5.5.1", "status": "unaffected"}], "lessThan": "*", "status": "affected", "version": "3.0.1", "versionType": "otp"}]}, {"collectionURL": "https://github.com", "cpes": ["cpe:2.3:a:erlang:erlang\\/otp:*:*:*:*:*:*:*:*"], "defaultStatus": "unaffected", "modules": ["ssh_transport"], "packageName": "erlang/otp", "packageURL": "pkg:github/erlang/otp", "product": "OTP", "programFiles": ["lib/ssh/src/ssh_transport.erl"], "programRoutines": [{"name": "ssh_transport:decompress/2"}, {"name": "ssh_transport:handle_packet_part/4"}], "repo": "https://github.com/erlang/otp", "vendor": "Erlang", "versions": [{"changes": [{"at": "0c1c04b191f6ab940e8fcfabce39eb5a8a6440a4", "status": "unaffected"}, {"at": "93073c3bd338c60cd2bae715ce6a1d4ffc1a8fd3", "status": "unaffected"}, {"at": "43a87b949bdff12d629a8c34146711d9da93b1b1", "status": "unaffected"}], "lessThan": "*", "status": "affected", "version": "07b8f441ca711f9812fad9e9115bab3c3aa92f79", "versionType": "git"}]}], "source": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db"}], "configurations": [{"nodes": [{"cpeMatch": [{"criteria": "cpe:2.3:a:erlang:erlang\\/otp:*:*:*:*:*:*:*:*", "matchCriteriaId": "6241E245-67D2-4FA6-83FE-4E9A4A07B3D1", "versionEndExcluding": "26.2.5.18", "versionStartIncluding": "17.0", "vulnerable": true}, {"criteria": "cpe:2.3:a:erlang:erlang\\/otp:*:*:*:*:*:*:*:*", "matchCriteriaId": "BE60BA92-431E-4DE3-A1C1-E8976E3A6BA7", "versionEndExcluding": "27.3.4.9", "versionStartIncluding": "27.0", "vulnerable": true}, {"criteria": "cpe:2.3:a:erlang:erlang\\/otp:*:*:*:*:*:*:*:*", "matchCriteriaId": "B8D9E80B-CA20-423A-A1A8-DEBB99D82BDB", "versionEndExcluding": "28.4.1", "versionStartIncluding": "28.0", "vulnerable": true}, {"criteria": "cpe:2.3:a:erlang:erlang\\/ssh:*:*:*:*:*:*:*:*", "matchCriteriaId": "24FD89BF-28BB-4432-9FDA-F0D84B5F716C", "versionEndExcluding": "5.1.4.14", "versionStartIncluding": "3.0.1", "vulnerable": true}, {"criteria": "cpe:2.3:a:erlang:erlang\\/ssh:*:*:*:*:*:*:*:*", "matchCriteriaId": "C0BFA1FA-14CC-4A47-A6A3-2572BA686367", "versionEndExcluding": "5.2.11.6", "versionStartIncluding": "5.2", "vulnerable": true}, {"criteria": "cpe:2.3:a:erlang:erlang\\/ssh:*:*:*:*:*:*:*:*", "matchCriteriaId": "0ABFC1FB-435C-414A-BF43-B119730E3DCE", "versionEndIncluding": "5.5.1", "versionStartIncluding": "5.5", "vulnerable": true}], "negate": false, "operator": "OR"}]}], "cveTags": [], "descriptions": [{"lang": "en", "value": "Improper Handling of Highly Compressed Data (Compression Bomb) vulnerability in Erlang OTP ssh (ssh_transport modules) allows Denial of Service via Resource Depletion.\n\nThe SSH transport layer advertises legacy zlib compression by default and inflates attacker-controlled payloads pre-authentication without any size limit, enabling reliable memory exhaustion DoS.\n\nTwo compression algorithms are affected:\n\n* zlib: Activates immediately after key exchange, enabling unauthenticated attacks\n* zlib@openssh.com: Activates post-authentication, enabling authenticated attacks\n\nEach SSH packet can decompress ~255 MB from 256 KB of wire data (1029:1 amplification ratio). Multiple packets can rapidly exhaust available memory, causing OOM kills in memory-constrained environments.\n\nThis vulnerability is associated with program files lib/ssh/src/ssh_transport.erl and program routines ssh_transport:decompress/2, ssh_transport:handle_packet_part/4.\n\nThis issue affects OTP from OTP\u00a017.0 before OTP\u00a026.2.5.18, OTP\u00a027.3.4.9, and OTP\u00a028.4.1, corresponding to ssh from 3.0.1 before 5.1.4.14, 5.2.11.6, and 5.5.1."}, {"lang": "es", "value": "La vulnerabilidad de Manejo Inadecuado de Datos Altamente Comprimidos (Bomba de Compresi\u00f3n) en Erlang OTP ssh (m\u00f3dulos ssh_transport) permite la denegaci\u00f3n de servicio mediante el agotamiento de recursos.\n\nLa capa de transporte SSH anuncia la compresi\u00f3n zlib heredada por defecto e infla cargas \u00fatiles controladas por el atacante pre-autenticaci\u00f3n sin ning\u00fan l\u00edmite de tama\u00f1o, lo que permite una DoS fiable por agotamiento de memoria.\n\nDos algoritmos de compresi\u00f3n se ven afectados:\n\n* zlib: Se activa inmediatamente despu\u00e9s del intercambio de claves, lo que permite ataques no autenticados\n* zlib@openssh.com: Se activa post-autenticaci\u00f3n, lo que permite ataques autenticados\n\nCada paquete SSH puede descomprimir ~255 MB de 256 KB de datos en la red (relaci\u00f3n de amplificaci\u00f3n de 1029:1). M\u00faltiples paquetes pueden agotar r\u00e1pidamente la memoria disponible, causando eliminaciones por OOM en entornos con memoria limitada.\n\nEsta vulnerabilidad est\u00e1 asociada con los archivos de programa lib/ssh/src/ssh_transport.erl y las rutinas de programa ssh_transport:decompress/2, ssh_transport:handle_packet_part/4.\n\nEste problema afecta a OTP desde OTP 17.0 hasta OTP 28.4.1, 27.3.4.9 y 26.2.5.18, lo que corresponde a ssh desde 3.0.1 hasta 5.5.1, 5.2.11.6 y 5.1.4.14."}], "id": "CVE-2026-23943", "lastModified": "2026-11-11T20:17:08.430", "metrics": {"cvssMetricV31": [{"cvssData": {"attackComplexity": "LOW", "attackVector": "NETWORK", "availabilityImpact": "LOW", "baseScore": 5.3, "baseSeverity": "MEDIUM", "confidentialityImpact": "NONE", "integrityImpact": "NONE", "privilegesRequired": "NONE", "scope": "UNCHANGED", "userInteraction": "NONE", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L", "version": "3.1"}, "exploitabilityScore": 3.9, "impactScore": 1.4, "source": "nvd@nist.gov", "type": "Primary"}], "cvssMetricV40": [{"cvssData": {"Automatable": "NOT_DEFINED", "Recovery": "NOT_DEFINED", "Safety": "NOT_DEFINED", "attackComplexity": "LOW", "attackRequirements": "NONE", "attackVector": "NETWORK", "availabilityRequirement": "NOT_DEFINED", "baseScore": 6.9, "baseSeverity": "MEDIUM", "confidentialityRequirement": "NOT_DEFINED", "exploitMaturity": "NOT_DEFINED", "integrityRequirement": "NOT_DEFINED", "modifiedAttackComplexity": "NOT_DEFINED", "modifiedAttackRequirements": "NOT_DEFINED", "modifiedAttackVector": "NOT_DEFINED", "modifiedPrivilegesRequired": "NOT_DEFINED", "modifiedSubAvailabilityImpact": "NOT_DEFINED", "modifiedSubConfidentialityImpact": "NOT_DEFINED", "modifiedSubIntegrityImpact": "NOT_DEFINED", "modifiedUserInteraction": "NOT_DEFINED", "modifiedVulnAvailabilityImpact": "NOT_DEFINED", "modifiedVulnConfidentialityImpact": "NOT_DEFINED", "modifiedVulnIntegrityImpact": "NOT_DEFINED", "privilegesRequired": "NONE", "providerUrgency": "NOT_DEFINED", "subAvailabilityImpact": "NONE", "subConfidentialityImpact": "NONE", "subIntegrityImpact": "NONE", "userInteraction": "NONE", "valueDensity": "NOT_DEFINED", "vectorString": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X", "version": "4.0", "vulnAvailabilityImpact": "LOW", "vulnConfidentialityImpact": "NONE", "vulnIntegrityImpact": "NONE", "vulnerabilityResponseEffort": "NOT_DEFINED"}, "source": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db", "type": "Secondary"}], "ssvcV203": [{"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "ssvcData": {"id": "CVE-2026-23943", "options": [{"exploitation": "none"}, {"automatable": "yes"}, {"technicalImpact": "partial"}], "role": "CISA Coordinator", "timestamp": "2026-03-13T16:01:40.898658Z", "version": "2.0.3"}}]}, "published": "2026-03-13T19:54:15.783", "references": [{"source": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db", "tags": ["Vendor Advisory"], "url": "https://cna.erlef.org/cves/CVE-2026-23943.html"}, {"source": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db", "url": "https://github.com/erlang/otp/commit/07b8f441ca711f9812fad9e9115bab3c3aa92f79"}, {"source": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db", "tags": ["Patch"], "url": "https://github.com/erlang/otp/commit/0c1c04b191f6ab940e8fcfabce39eb5a8a6440a4"}, {"source": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db", "tags": ["Patch"], "url": "https://github.com/erlang/otp/commit/43a87b949bdff12d629a8c34146711d9da93b1b1"}, {"source": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db", "tags": ["Patch"], "url": "https://github.com/erlang/otp/commit/93073c3bd338c60cd2bae715ce6a1d4ffc1a8fd3"}, {"source": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db", "tags": ["Vendor Advisory"], "url": "https://github.com/erlang/otp/security/advisories/GHSA-c836-qprm-jw9r"}, {"source": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db", "tags": ["Third Party Advisory"], "url": "https://osv.dev/vulnerability/EEF-CVE-2026-23943"}, {"source": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db", "tags": ["Product"], "url": "https://www.erlang.org/doc/system/versions.html#order-of-versions"}], "sourceIdentifier": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db", "vulnStatus": "Modified", "weaknesses": [{"description": [{"lang": "en", "value": "CWE-409"}], "source": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db", "type": "Secondary"}]}

{}

{"affected": [{"configurations": [{"platform": null, "status": "affected", "versions": {"scheme": "semver", "value": "[3.0.1,*]"}}, {"platform": null, "status": "affected", "versions": {"scheme": "generic", "value": "[pkg:otp/ssh@3.0.1,pkg:otp/ssh@*]"}}, {"platform": null, "status": "affected", "versions": {"scheme": "semver", "value": "[17.0,*]"}}, {"platform": null, "status": "affected", "versions": {"scheme": "code_commit", "value": "[07b8f441ca711f9812fad9e9115bab3c3aa92f79,*]"}}], "enrichment": {"confidence": 90.0, "confidence_source": "inferred", "scores": [{"score": 90.0, "source": "inferred"}, {"score": 100.0, "source": "matching"}]}, "product": "erlang/otp", "vendor": "erlang"}, {"configurations": [{"platform": null, "status": "affected", "versions": {"scheme": "semver", "value": "[3.0.1,*]"}}, {"platform": null, "status": "affected", "versions": {"scheme": "generic", "value": "[pkg:otp/ssh@3.0.1,pkg:otp/ssh@*]"}}], "enrichment": {"confidence": 100.0, "confidence_source": "matching", "scores": [{"score": 100.0, "source": "matching"}]}, "original": {"product": "OTP", "source": "cna", "vendor": "Erlang"}, "product": "otp", "vendor": "erlang"}, {"configurations": [{"platform": null, "status": "affected", "versions": {"scheme": "semver", "value": "[17.0,*]"}}, {"platform": null, "status": "affected", "versions": {"scheme": "code_commit", "value": "[07b8f441ca711f9812fad9e9115bab3c3aa92f79,*]"}}], "enrichment": {"confidence": 100.0, "confidence_source": "matching", "scores": [{"score": 100.0, "source": "matching"}]}, "original": {"product": "OTP", "source": "cna", "vendor": "Erlang"}, "product": "otp", "vendor": "erlang"}], "created": "2026-03-16T09:37:49.019975+00:00", "updated": "2026-08-03T08:15:03.624779+00:00", "vendors": ["erlang", "erlang$PRODUCT$erlang/otp", "erlang$PRODUCT$otp"]}