CVE-2021-3634

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{"affected": [{"affectedData": [{"product": "libssh", "vendor": "n/a", "versions": [{"status": "affected", "version": "libssh 0.9.6"}]}], "source": "secalert@redhat.com"}], "configurations": [{"nodes": [{"cpeMatch": [{"criteria": "cpe:2.3:a:libssh:libssh:*:*:*:*:*:*:*:*", "matchCriteriaId": "45D76734-EC25-46B5-BA69-C3A6809CB194", "versionEndExcluding": "0.9.6", "versionStartIncluding": "0.9.1", "vulnerable": true}], "negate": false, "operator": "OR"}]}, {"nodes": [{"cpeMatch": [{"criteria": "cpe:2.3:a:redhat:virtualization:4.0:*:*:*:*:*:*:*", "matchCriteriaId": "6BBD7A51-0590-4DDF-8249-5AFA8D645CB6", "vulnerable": true}, {"criteria": "cpe:2.3:o:redhat:enterprise_linux:8.0:*:*:*:-:*:*:*", "matchCriteriaId": "053C1B35-3869-41C2-9551-044182DE0A64", "vulnerable": true}], "negate": false, "operator": "OR"}]}, {"nodes": [{"cpeMatch": [{"criteria": "cpe:2.3:o:debian:debian_linux:10.0:*:*:*:*:*:*:*", "matchCriteriaId": "07B237A9-69A3-4A9C-9DA0-4E06BD37AE73", "vulnerable": true}, {"criteria": "cpe:2.3:o:debian:debian_linux:11.0:*:*:*:*:*:*:*", "matchCriteriaId": "FA6FEEC2-9F11-4643-8827-749718254FED", "vulnerable": true}], "negate": false, "operator": "OR"}]}, {"nodes": [{"cpeMatch": [{"criteria": "cpe:2.3:o:fedoraproject:fedora:33:*:*:*:*:*:*:*", "matchCriteriaId": "E460AA51-FCDA-46B9-AE97-E6676AA5E194", "vulnerable": true}, {"criteria": "cpe:2.3:o:fedoraproject:fedora:34:*:*:*:*:*:*:*", "matchCriteriaId": "A930E247-0B43-43CB-98FF-6CE7B8189835", "vulnerable": true}, {"criteria": "cpe:2.3:o:fedoraproject:fedora:35:*:*:*:*:*:*:*", "matchCriteriaId": "80E516C0-98A4-4ADE-B69F-66A772E2BAAA", "vulnerable": true}], "negate": false, "operator": "OR"}]}, {"nodes": [{"cpeMatch": [{"criteria": "cpe:2.3:a:oracle:mysql_workbench:*:*:*:*:*:*:*:*", "matchCriteriaId": "6B9C558D-B200-45F2-9575-0816A10C58FA", "versionEndIncluding": "8.0.27", "vulnerable": true}], "negate": false, "operator": "OR"}]}, {"nodes": [{"cpeMatch": [{"criteria": "cpe:2.3:a:netapp:cloud_backup:-:*:*:*:*:*:*:*", "matchCriteriaId": "5C2089EE-5D7F-47EC-8EA5-0F69790564C4", "vulnerable": true}], "negate": false, "operator": "OR"}]}], "cveTags": [], "descriptions": [{"lang": "en", "value": "A flaw has been found in libssh in versions prior to 0.9.6. The SSH protocol keeps track of two shared secrets during the lifetime of the session. One of them is called secret_hash and the other session_id. Initially, both of them are the same, but after key re-exchange, previous session_id is kept and used as an input to new secret_hash. Historically, both of these buffers had shared length variable, which worked as long as these buffers were same. But the key re-exchange operation can also change the key exchange method, which can be based on hash of different size, eventually creating \"secret_hash\" of different size than the session_id has. This becomes an issue when the session_id memory is zeroed or when it is used again during second key re-exchange."}, {"lang": "es", "value": "Se ha encontrado un fallo en libssh en versiones anteriores a 0.9.6. El protocolo SSH mantiene un registro de dos secretos compartidos durante el tiempo de la sesi\u00f3n. Uno de ellos se llama secret_hash y el otro session_id. Inicialmente, ambos son el mismo, pero despu\u00e9s del recambio de claves, el session_id anterior es mantenida y usada como entrada para el nuevo secret_hash. Hist\u00f3ricamente, ambos b\u00faferes ten\u00edan una variable de longitud compartida, que funcionaba mientras estos b\u00faferes eran iguales. Pero la operaci\u00f3n de recambio de claves tambi\u00e9n puede cambiar el m\u00e9todo de intercambio de claves, que puede ser basado en un hash de diferente tama\u00f1o, creando eventualmente \"secret_hash\" de diferente tama\u00f1o que el session_id presenta. Esto se convierte en un problema cuando la memoria de session_id se pone a cero o cuando es usada de nuevo durante el segundo intercambio de claves"}], "id": "CVE-2021-3634", "lastModified": "2026-06-17T04:05:28.780", "metrics": {"cvssMetricV2": [{"acInsufInfo": false, "baseSeverity": "MEDIUM", "cvssData": {"accessComplexity": "LOW", "accessVector": "NETWORK", "authentication": "SINGLE", "availabilityImpact": "PARTIAL", "baseScore": 4.0, "confidentialityImpact": "NONE", "integrityImpact": "NONE", "vectorString": "AV:N/AC:L/Au:S/C:N/I:N/A:P", "version": "2.0"}, "exploitabilityScore": 8.0, "impactScore": 2.9, "obtainAllPrivilege": false, "obtainOtherPrivilege": false, "obtainUserPrivilege": false, "source": "nvd@nist.gov", "type": "Primary", "userInteractionRequired": false}], "cvssMetricV31": [{"cvssData": {"attackComplexity": "LOW", "attackVector": "NETWORK", "availabilityImpact": "HIGH", "baseScore": 6.5, "baseSeverity": "MEDIUM", "confidentialityImpact": "NONE", "integrityImpact": "NONE", "privilegesRequired": "LOW", "scope": "UNCHANGED", "userInteraction": "NONE", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H", "version": "3.1"}, "exploitabilityScore": 2.8, "impactScore": 3.6, "source": "nvd@nist.gov", "type": "Primary"}]}, "published": "2021-08-31T17:15:08.323", "references": [{"source": "secalert@redhat.com", "tags": ["Issue Tracking", "Third Party Advisory"], "url": "https://bugzilla.redhat.com/show_bug.cgi?id=1978810"}, {"source": "secalert@redhat.com", "url": "https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/DRK67AJCWYYVAGF5SGAHNZXCX3PN3ZFP/"}, {"source": "secalert@redhat.com", "url": "https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/JKYD3ZRAMDAQX3ZW6THHUF3GXN7FF6B4/"}, {"source": "secalert@redhat.com", "url": "https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/SVWAAB2XMKEUMPMDALINKAA4U2QM4LNG/"}, {"source": "secalert@redhat.com", "url": "https://security.gentoo.org/glsa/202312-05"}, {"source": "secalert@redhat.com", "tags": ["Third Party Advisory"], "url": "https://security.netapp.com/advisory/ntap-20211004-0003/"}, {"source": "secalert@redhat.com", "tags": ["Third Party Advisory"], "url": "https://www.debian.org/security/2021/dsa-4965"}, {"source": "secalert@redhat.com", "tags": ["Patch", "Third Party Advisory"], "url": "https://www.oracle.com/security-alerts/cpujan2022.html"}, {"source": "af854a3a-2127-422b-91ae-364da2661108", "tags": ["Issue Tracking", "Third Party Advisory"], "url": "https://bugzilla.redhat.com/show_bug.cgi?id=1978810"}, {"source": "af854a3a-2127-422b-91ae-364da2661108", "url": "https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/DRK67AJCWYYVAGF5SGAHNZXCX3PN3ZFP/"}, {"source": "af854a3a-2127-422b-91ae-364da2661108", "url": "https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/JKYD3ZRAMDAQX3ZW6THHUF3GXN7FF6B4/"}, {"source": "af854a3a-2127-422b-91ae-364da2661108", "url": "https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/SVWAAB2XMKEUMPMDALINKAA4U2QM4LNG/"}, {"source": "af854a3a-2127-422b-91ae-364da2661108", "url": "https://security.gentoo.org/glsa/202312-05"}, {"source": "af854a3a-2127-422b-91ae-364da2661108", "tags": ["Third Party Advisory"], "url": "https://security.netapp.com/advisory/ntap-20211004-0003/"}, {"source": "af854a3a-2127-422b-91ae-364da2661108", "tags": ["Third Party Advisory"], "url": "https://www.debian.org/security/2021/dsa-4965"}, {"source": "af854a3a-2127-422b-91ae-364da2661108", "tags": ["Patch", "Third Party Advisory"], "url": "https://www.oracle.com/security-alerts/cpujan2022.html"}], "sourceIdentifier": "secalert@redhat.com", "vulnStatus": "Modified", "weaknesses": [{"description": [{"lang": "en", "value": "CWE-787"}], "source": "secalert@redhat.com", "type": "Secondary"}, {"description": [{"lang": "en", "value": "CWE-787"}], "source": "nvd@nist.gov", "type": "Primary"}]}

{"affected_release": [{"advisory": "RHSA-2022:2031", "cpe": "cpe:/a:redhat:enterprise_linux:8", "package": "libssh-0:0.9.6-3.el8", "product_name": "Red Hat Enterprise Linux 8", "release_date": "2022-05-10T00:00:00Z"}, {"advisory": "RHSA-2022:2031", "cpe": "cpe:/o:redhat:enterprise_linux:8", "package": "libssh-0:0.9.6-3.el8", "product_name": "Red Hat Enterprise Linux 8", "release_date": "2022-05-10T00:00:00Z"}], "bugzilla": {"description": "libssh: possible heap-based buffer overflow when rekeying", "id": "1978810", "url": "https://bugzilla.redhat.com/show_bug.cgi?id=1978810"}, "csaw": false, "cvss3": {"cvss3_base_score": "3.5", "cvss3_scoring_vector": "CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:N/I:N/A:L", "status": "verified"}, "cwe": "CWE-787", "details": ["A flaw has been found in libssh in versions prior to 0.9.6. The SSH protocol keeps track of two shared secrets during the lifetime of the session. One of them is called secret_hash and the other session_id. Initially, both of them are the same, but after key re-exchange, previous session_id is kept and used as an input to new secret_hash. Historically, both of these buffers had shared length variable, which worked as long as these buffers were same. But the key re-exchange operation can also change the key exchange method, which can be based on hash of different size, eventually creating \"secret_hash\" of different size than the session_id has. This becomes an issue when the session_id memory is zeroed or when it is used again during second key re-exchange.", "A flaw has been found in libssh. The SSH protocol keeps track of two shared secrets during the lifetime of the session. One of them is called secret_hash and the other session_id. Initially, both of them are the same, but after key re-exchange, previous session_id is kept and used as an input to new secret_hash. Historically, both of these buffers had shared length variable, which worked as long as these buffers were same. But the key re-exchange operation can also change the key exchange method, which can be based on hash of different size, eventually creating \"secret_hash\" of different size than the session_id has. This becomes an issue when the session_id memory is zeroed or when it is used again during second key re-exchange."], "name": "CVE-2021-3634", "package_state": [{"cpe": "cpe:/o:redhat:enterprise_linux:7", "fix_state": "Out of support scope", "package_name": "libssh", "product_name": "Red Hat Enterprise Linux 7"}, {"cpe": "cpe:/o:redhat:enterprise_linux:9", "fix_state": "Not affected", "package_name": "libssh", "product_name": "Red Hat Enterprise Linux 9"}, {"cpe": "cpe:/o:redhat:rhev_hypervisor:4", "fix_state": "Out of support scope", "package_name": "libssh", "product_name": "Red Hat Virtualization 4"}], "public_date": "2021-08-26T13:19:00Z", "references": ["https://www.cve.org/CVERecord?id=CVE-2021-3634\nhttps://nvd.nist.gov/vuln/detail/CVE-2021-3634"], "threat_severity": "Low"}

{}