CVE-2026-64389

{"dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": {"cveId": "CVE-2026-64389", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2026-07-19T15:36:31.785Z", "datePublished": "2026-07-25T08:50:36.817Z", "dateUpdated": "2026-10-30T12:27:50.295Z"}, "containers": {"cna": {"providerMetadata": {"orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-10-30T12:27:50.295Z"}, "descriptions": [{"lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nksmbd: validate NTLMv2 response before updating session key\n\nksmbd_auth_ntlmv2() derives the NTLMv2 session key into\nsess->sess_key before it verifies the NTLMv2 response.\nksmbd_decode_ntlmssp_auth_blob() then continues into KEY_XCH even\nwhen ksmbd_auth_ntlmv2() failed.\n\nWith SMB3 multichannel binding, the failed authentication operates on\nan existing session and the session setup error path does not expire\nbinding sessions. A client can send a binding session setup with a\nbad NT proof and KEY_XCH and still modify sess->sess_key before\nSTATUS_LOGON_FAILURE is returned.\n\nRelevant path:\n\n smb2_sess_setup()\n -> conn->binding = true\n -> ntlm_authenticate()\n -> session_user()\n -> ksmbd_decode_ntlmssp_auth_blob()\n -> ksmbd_auth_ntlmv2()\n -> calc_ntlmv2_hash()\n -> hmac_md5_usingrawkey(..., sess->sess_key)\n -> crypto_memneq() returns mismatch\n -> KEY_XCH arc4_crypt(..., sess->sess_key, ...)\n -> out_err without expiring the binding session\n\nDerive the base session key into a local buffer and copy it to\nsess->sess_key only after the proof matches. Return immediately on\nauthentication failure so KEY_XCH is only processed after successful\nauthentication."}], "metrics": [{"cvssV3_1": {"version": "3.1", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:H", "baseScore": 8.2, "baseSeverity": "HIGH"}, "scenarios": [{"lang": "en", "value": "AV:N - The vulnerable NTLMv2 authentication path is reached remotely through ksmbd SESSION_SETUP requests over SMB on TCP/445.\nAC:L - An attacker can deterministically trigger the key overwrite using a malformed multichannel binding request with KEY_XCH; no race or condition beyond attacker control is required.\nPR:N - The overwrite occurs before NTLMv2 proof validation, and the affected code does not verify the binding request signature, so valid credentials or an authenticated attacker session are unnecessary.\nUI:N - No victim action is required beyond an active SMB session, which can belong to an automated client or service.\nS:U - The corrupted session state and resulting effects remain within the ksmbd server and host kernel security authority.\nC:N - The bounded session-key overwrite does not disclose the prior key, kernel memory, or protected SMB data.\nI:L - The attacker can modify an established session's security-critical key state, but cannot reliably select the resulting key or obtain an arbitrary memory or file-write primitive.\nA:H - Repeated unauthenticated key corruption can desynchronize signing-key derivation and render targeted multichannel binding or session recovery unusable, causing complete loss of the affected SMB session in dependent deployments."}]}], "affected": [{"product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": ["fs/smb/server/auth.c"], "versions": [{"version": "e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9", "lessThan": "e589e997bddde0a6f45672dd871cba7b3ff28e17", "status": "affected", "versionType": "git"}, {"version": "e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9", "lessThan": "a6a951416b55eaf51ea2742f7ba786f240e70137", "status": "affected", "versionType": "git"}, {"version": "e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9", "lessThan": "f5d74c186bab26a5d5a025305e67edd0888aa34d", "status": "affected", "versionType": "git"}, {"version": "e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9", "lessThan": "b56400364aed5c34d6e1a0b493081290a5328a9c", "status": "affected", "versionType": "git"}, {"version": "e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9", "lessThan": "89ca7756d5566ba636bb9092cdbe57dab095e136", "status": "affected", "versionType": "git"}, {"version": "e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9", "lessThan": "954d196bebb2b50151cb96454c72dc113b2af1ac", "status": "affected", "versionType": "git"}]}, {"product": "Linux", "vendor": "Linux", "defaultStatus": "affected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": ["fs/smb/server/auth.c"], "versions": [{"version": "5.15", "status": "affected"}, {"version": "0", "lessThan": "5.15", "status": "unaffected", "versionType": "semver"}, {"version": "6.1.191", "lessThanOrEqual": "6.1.*", "status": "unaffected", "versionType": "semver"}, {"version": "6.6.160", "lessThanOrEqual": "6.6.*", "status": "unaffected", "versionType": "semver"}, {"version": "6.12.114", "lessThanOrEqual": "6.12.*", "status": "unaffected", "versionType": "semver"}, {"version": "6.18.40", "lessThanOrEqual": "6.18.*", "status": "unaffected", "versionType": "semver"}, {"version": "7.1.4", "lessThanOrEqual": "7.1.*", "status": "unaffected", "versionType": "semver"}, {"version": "7.2", "lessThanOrEqual": "*", "status": "unaffected", "versionType": "original_commit_for_fix"}]}], "cpeApplicability": [{"nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.15", "versionEndExcluding": "6.1.191"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.15", "versionEndExcluding": "6.6.160"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.15", "versionEndExcluding": "6.12.114"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.15", "versionEndExcluding": "6.18.40"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.15", "versionEndExcluding": "7.1.4"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.15", "versionEndExcluding": "7.2"}]}]}], "references": [{"url": "https://git.kernel.org/stable/c/e589e997bddde0a6f45672dd871cba7b3ff28e17"}, {"url": "https://git.kernel.org/stable/c/a6a951416b55eaf51ea2742f7ba786f240e70137"}, {"url": "https://git.kernel.org/stable/c/f5d74c186bab26a5d5a025305e67edd0888aa34d"}, {"url": "https://git.kernel.org/stable/c/b56400364aed5c34d6e1a0b493081290a5328a9c"}, {"url": "https://git.kernel.org/stable/c/89ca7756d5566ba636bb9092cdbe57dab095e136"}, {"url": "https://git.kernel.org/stable/c/954d196bebb2b50151cb96454c72dc113b2af1ac"}], "title": "ksmbd: validate NTLMv2 response before updating session key", "x_generator": {"engine": "bippy-1.2.0"}}}}

{}

{"affected": [{"affectedData": [{"defaultStatus": "unaffected", "product": "Linux", "programFiles": ["fs/smb/server/auth.c"], "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "vendor": "Linux", "versions": [{"lessThan": "e589e997bddde0a6f45672dd871cba7b3ff28e17", "status": "affected", "version": "e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9", "versionType": "git"}, {"lessThan": "a6a951416b55eaf51ea2742f7ba786f240e70137", "status": "affected", "version": "e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9", "versionType": "git"}, {"lessThan": "f5d74c186bab26a5d5a025305e67edd0888aa34d", "status": "affected", "version": "e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9", "versionType": "git"}, {"lessThan": "b56400364aed5c34d6e1a0b493081290a5328a9c", "status": "affected", "version": "e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9", "versionType": "git"}, {"lessThan": "89ca7756d5566ba636bb9092cdbe57dab095e136", "status": "affected", "version": "e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9", "versionType": "git"}, {"lessThan": "954d196bebb2b50151cb96454c72dc113b2af1ac", "status": "affected", "version": "e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9", "versionType": "git"}]}, {"defaultStatus": "affected", "product": "Linux", "programFiles": ["fs/smb/server/auth.c"], "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "vendor": "Linux", "versions": [{"status": "affected", "version": "5.15"}, {"lessThan": "5.15", "status": "unaffected", "version": "0", "versionType": "semver"}, {"lessThanOrEqual": "6.1.*", "status": "unaffected", "version": "6.1.191", "versionType": "semver"}, {"lessThanOrEqual": "6.6.*", "status": "unaffected", "version": "6.6.160", "versionType": "semver"}, {"lessThanOrEqual": "6.12.*", "status": "unaffected", "version": "6.12.114", "versionType": "semver"}, {"lessThanOrEqual": "6.18.*", "status": "unaffected", "version": "6.18.40", "versionType": "semver"}, {"lessThanOrEqual": "7.1.*", "status": "unaffected", "version": "7.1.4", "versionType": "semver"}, {"lessThanOrEqual": "*", "status": "unaffected", "version": "7.2", "versionType": "original_commit_for_fix"}]}], "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"}], "configurations": [{"nodes": [{"cpeMatch": [{"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "matchCriteriaId": "DBEC5A00-0484-47F0-BD82-5461DC6C7A5C", "versionEndExcluding": "6.18.40", "versionStartIncluding": "5.15", "vulnerable": true}, {"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "matchCriteriaId": "6228DDD6-4557-4AA3-9F43-AB995D471E42", "versionEndExcluding": "7.1.4", "versionStartIncluding": "6.19", "vulnerable": true}], "negate": false, "operator": "OR"}]}], "cveTags": [], "descriptions": [{"lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nksmbd: validate NTLMv2 response before updating session key\n\nksmbd_auth_ntlmv2() derives the NTLMv2 session key into\nsess->sess_key before it verifies the NTLMv2 response.\nksmbd_decode_ntlmssp_auth_blob() then continues into KEY_XCH even\nwhen ksmbd_auth_ntlmv2() failed.\n\nWith SMB3 multichannel binding, the failed authentication operates on\nan existing session and the session setup error path does not expire\nbinding sessions. A client can send a binding session setup with a\nbad NT proof and KEY_XCH and still modify sess->sess_key before\nSTATUS_LOGON_FAILURE is returned.\n\nRelevant path:\n\n smb2_sess_setup()\n -> conn->binding = true\n -> ntlm_authenticate()\n -> session_user()\n -> ksmbd_decode_ntlmssp_auth_blob()\n -> ksmbd_auth_ntlmv2()\n -> calc_ntlmv2_hash()\n -> hmac_md5_usingrawkey(..., sess->sess_key)\n -> crypto_memneq() returns mismatch\n -> KEY_XCH arc4_crypt(..., sess->sess_key, ...)\n -> out_err without expiring the binding session\n\nDerive the base session key into a local buffer and copy it to\nsess->sess_key only after the proof matches. Return immediately on\nauthentication failure so KEY_XCH is only processed after successful\nauthentication."}], "id": "CVE-2026-64389", "lastModified": "2026-10-30T13:19:35.700", "metrics": {"cvssMetricV31": [{"cvssData": {"attackComplexity": "LOW", "attackVector": "NETWORK", "availabilityImpact": "HIGH", "baseScore": 8.2, "baseSeverity": "HIGH", "confidentialityImpact": "NONE", "integrityImpact": "LOW", "privilegesRequired": "NONE", "scope": "UNCHANGED", "userInteraction": "NONE", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:H", "version": "3.1"}, "exploitabilityScore": 3.9, "impactScore": 4.2, "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "type": "Secondary"}]}, "published": "2026-07-25T10:17:22.227", "references": [{"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"], "url": "https://git.kernel.org/stable/c/89ca7756d5566ba636bb9092cdbe57dab095e136"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"], "url": "https://git.kernel.org/stable/c/954d196bebb2b50151cb96454c72dc113b2af1ac"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/a6a951416b55eaf51ea2742f7ba786f240e70137"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"], "url": "https://git.kernel.org/stable/c/b56400364aed5c34d6e1a0b493081290a5328a9c"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/e589e997bddde0a6f45672dd871cba7b3ff28e17"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/f5d74c186bab26a5d5a025305e67edd0888aa34d"}], "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "vulnStatus": "Modified", "weaknesses": [{"description": [{"lang": "en", "value": "NVD-CWE-noinfo"}], "source": "nvd@nist.gov", "type": "Primary"}]}

{"bugzilla": {"description": "kernel: ksmbd: validate NTLMv2 response before updating session key", "id": "2507112", "url": "https://bugzilla.redhat.com/show_bug.cgi?id=2507112"}, "csaw": false, "cwe": "CWE-179", "details": ["A flaw was found in the Linux kernel's ksmbd component. A remote attacker could exploit a vulnerability in the NTLMv2 authentication process to modify a session key even when authentication fails. This bypasses security checks and could potentially lead to unauthorized access or session hijacking."], "name": "CVE-2026-64389", "package_state": [{"cpe": "cpe:/o:redhat:enterprise_linux:10", "fix_state": "Not affected", "package_name": "kernel", "product_name": "Red Hat Enterprise Linux 10"}, {"cpe": "cpe:/o:redhat:enterprise_linux:6", "fix_state": "Not affected", "package_name": "kernel", "product_name": "Red Hat Enterprise Linux 6"}, {"cpe": "cpe:/o:redhat:enterprise_linux:7", "fix_state": "Not affected", "package_name": "kernel", "product_name": "Red Hat Enterprise Linux 7"}, {"cpe": "cpe:/o:redhat:enterprise_linux:7", "fix_state": "Not affected", "package_name": "kernel-rt", "product_name": "Red Hat Enterprise Linux 7"}, {"cpe": "cpe:/o:redhat:enterprise_linux:8", "fix_state": "Not affected", "package_name": "kernel", "product_name": "Red Hat Enterprise Linux 8"}, {"cpe": "cpe:/o:redhat:enterprise_linux:8", "fix_state": "Not affected", "package_name": "kernel-rt", "product_name": "Red Hat Enterprise Linux 8"}, {"cpe": "cpe:/o:redhat:enterprise_linux:9", "fix_state": "Not affected", "package_name": "kernel", "product_name": "Red Hat Enterprise Linux 9"}, {"cpe": "cpe:/o:redhat:enterprise_linux:9", "fix_state": "Not affected", "package_name": "kernel-rt", "product_name": "Red Hat Enterprise Linux 9"}, {"cpe": "cpe:/a:redhat:hummingbird:1", "fix_state": "Affected", "impact": "moderate", "package_name": "erlang27", "product_name": "Red Hat Hardened Images"}], "public_date": "2026-07-25T00:00:00Z", "references": ["https://www.cve.org/CVERecord?id=CVE-2026-64389\nhttps://nvd.nist.gov/vuln/detail/CVE-2026-64389\nhttps://lore.kernel.org/linux-cve-announce/2026072527-CVE-2026-64389-de36@gregkh/T"]}

{"affected": [{"configurations": [{"platform": null, "status": "affected", "versions": {"scheme": "code_commit", "value": "[e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9,b56400364aed5c34d6e1a0b493081290a5328a9c)"}}, {"platform": null, "status": "affected", "versions": {"scheme": "code_commit", "value": "[e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9,89ca7756d5566ba636bb9092cdbe57dab095e136)"}}, {"platform": null, "status": "affected", "versions": {"scheme": "code_commit", "value": "[e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9,954d196bebb2b50151cb96454c72dc113b2af1ac)"}}], "enrichment": {"confidence": 99.0, "confidence_source": "inferred", "scores": [{"score": 99.0, "source": "inferred"}, {"score": 100.0, "source": "matching"}]}, "original": {"product": "Linux", "source": "cna", "vendor": "Linux"}, "product": "linux_kernel", "vendor": "linux"}, {"configurations": [{"platform": null, "status": "affected", "versions": {"scheme": "semver", "value": "5.15"}}, {"platform": null, "status": "unaffected", "versions": {"scheme": "semver", "value": "[0,5.15)"}}, {"platform": null, "status": "unaffected", "versions": {"scheme": "semver", "value": "[6.18.40,6.19.0)"}}, {"platform": null, "status": "unaffected", "versions": {"scheme": "semver", "value": "[7.1.4,7.2.0)"}}, {"platform": null, "status": "unaffected", "versions": {"scheme": "generic", "value": "[7.2-rc1,*]"}}], "enrichment": {"confidence": 99.0, "confidence_source": "inferred", "scores": [{"score": 99.0, "source": "inferred"}, {"score": 100.0, "source": "matching"}]}, "original": {"product": "Linux", "source": "cna", "vendor": "Linux"}, "product": "linux_kernel", "vendor": "linux"}], "created": "2026-07-25T16:15:18.042022+00:00", "updated": "2026-09-04T23:30:06.530085+00:00", "vendors": ["linux", "linux$PRODUCT$linux_kernel"]}