{"id":"CVE-2026-53583","state":"PUBLISHED","title":"libgit2: Inverted IP SubjectAltName Comparison in OpenSSL Backend","description":"libgit2 is a portable C implementation of the Git core methods provided as a linkable library with a solid API, allowing to build Git functionality into your application. Prior to 1.8.6 and 1.9.5, verify_server_cert in src/libgit2/streams/openssl.c uses an inverted !!memcmp result in the GEN_IPADD branch when comparing an IP-literal host with a certificate IP SubjectAltName. OpenSSL builds reject matching IP addresses and accept mismatched IP addresses, allowing a network attacker with a CA-trusted certificate containing any IP SubjectAltName to intercept libgit2 connections to IP-literal HTTPS URLs. DNS SubjectAltName validation and non-OpenSSL TLS backends are not affected. This issue is fixed in versions 1.8.6 and 1.9.5.","publishedAt":"2026-08-20T18:39:03.676Z","updatedAt":"2026-08-20T19:04:42.247Z","severity":{"score":6.5,"label":"Medium","version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N","source":"GitHub_M"},"assigner":"GitHub_M","products":["libgit2 libgit2"],"affected":[{"vendor":"libgit2","product":"libgit2","versions":[{"version":"< 1.8.6","status":"affected"},{"version":">= 1.9.0, < 1.9.5","status":"affected"}]}],"references":["https://github.com/libgit2/libgit2/security/advisories/GHSA-h7gc-w2gg-p9xp","https://github.com/libgit2/libgit2/commit/647dcb432980b84ede4cb5a008bbd1ccb4ead03d","https://github.com/libgit2/libgit2/commit/c2aa35409ee0e6515df64da49750f13a0a42c47f","https://github.com/libgit2/libgit2/commit/ef086bc3e4eedf62be38a910381aae24d49871ff","https://github.com/libgit2/libgit2/releases/tag/v1.8.6","https://github.com/libgit2/libgit2/releases/tag/v1.9.5"],"weaknesses":["CWE-295","CWE-297"],"ingestedAt":"2026-10-29T20:12:16.098Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/53xxx/CVE-2026-53583.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-53583","state":"PUBLISHED","datePublished":"2026-08-20T18:39:03.676Z","dateUpdated":"2026-08-20T19:04:42.247Z","assignerShortName":"GitHub_M","assignerOrgId":"a0819718-46f1-4df5-94e2-005712e83aaa","dateReserved":"2026-06-09T19:11:53.484Z"},"containers":{"cna":{"title":"libgit2: Inverted IP SubjectAltName Comparison in OpenSSL Backend","descriptions":[{"lang":"en","value":"libgit2 is a portable C implementation of the Git core methods provided as a linkable library with a solid API, allowing to build Git functionality into your application. Prior to 1.8.6 and 1.9.5, verify_server_cert in src/libgit2/streams/openssl.c uses an inverted !!memcmp result in the GEN_IPADD branch when comparing an IP-literal host with a certificate IP SubjectAltName. OpenSSL builds reject matching IP addresses and accept mismatched IP addresses, allowing a network attacker with a CA-trusted certificate containing any IP SubjectAltName to intercept libgit2 connections to IP-literal HTTPS URLs. DNS SubjectAltName validation and non-OpenSSL TLS backends are not affected. This issue is fixed in versions 1.8.6 and 1.9.5."}],"affected":[{"vendor":"libgit2","product":"libgit2","versions":[{"version":"< 1.8.6","status":"affected"},{"version":">= 1.9.0, < 1.9.5","status":"affected"}]}],"references":[{"url":"https://github.com/libgit2/libgit2/security/advisories/GHSA-h7gc-w2gg-p9xp","name":"https://github.com/libgit2/libgit2/security/advisories/GHSA-h7gc-w2gg-p9xp","tags":["x_refsource_CONFIRM"]},{"url":"https://github.com/libgit2/libgit2/commit/647dcb432980b84ede4cb5a008bbd1ccb4ead03d","name":"https://github.com/libgit2/libgit2/commit/647dcb432980b84ede4cb5a008bbd1ccb4ead03d","tags":["x_refsource_MISC"]},{"url":"https://github.com/libgit2/libgit2/commit/c2aa35409ee0e6515df64da49750f13a0a42c47f","name":"https://github.com/libgit2/libgit2/commit/c2aa35409ee0e6515df64da49750f13a0a42c47f","tags":["x_refsource_MISC"]},{"url":"https://github.com/libgit2/libgit2/commit/ef086bc3e4eedf62be38a910381aae24d49871ff","name":"https://github.com/libgit2/libgit2/commit/ef086bc3e4eedf62be38a910381aae24d49871ff","tags":["x_refsource_MISC"]},{"url":"https://github.com/libgit2/libgit2/releases/tag/v1.8.6","name":"https://github.com/libgit2/libgit2/releases/tag/v1.8.6","tags":["x_refsource_MISC"]},{"url":"https://github.com/libgit2/libgit2/releases/tag/v1.9.5","name":"https://github.com/libgit2/libgit2/releases/tag/v1.9.5","tags":["x_refsource_MISC"]}],"metrics":[{"cvssV3_1":{"attackComplexity":"LOW","attackVector":"NETWORK","availabilityImpact":"NONE","baseScore":6.5,"baseSeverity":"MEDIUM","confidentialityImpact":"LOW","integrityImpact":"LOW","privilegesRequired":"NONE","scope":"UNCHANGED","userInteraction":"NONE","vectorString":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N","version":"3.1"}}],"problemTypes":[{"descriptions":[{"cweId":"CWE-295","lang":"en","description":"CWE-295: Improper Certificate Validation","type":"CWE"}]},{"descriptions":[{"cweId":"CWE-297","lang":"en","description":"CWE-297: Improper Validation of Certificate with Host Mismatch","type":"CWE"}]}],"providerMetadata":{"shortName":"GitHub_M","orgId":"a0819718-46f1-4df5-94e2-005712e83aaa","dateUpdated":"2026-08-20T18:39:03.676Z"},"source":{"advisory":"GHSA-h7gc-w2gg-p9xp","discovery":"UNKNOWN"}},"adp":[{"title":"CISA ADP Vulnrichment","references":[{"url":"https://github.com/libgit2/libgit2/security/advisories/GHSA-h7gc-w2gg-p9xp","tags":["exploit"]}],"metrics":[{"other":{"type":"ssvc","content":{"timestamp":"2026-08-20T19:03:44.491440Z","id":"CVE-2026-53583","options":[{"Exploitation":"poc"},{"Automatable":"yes"},{"Technical Impact":"partial"}],"role":"CISA Coordinator","version":"2.0.3"}}}],"providerMetadata":{"shortName":"CISA-ADP","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","dateUpdated":"2026-08-20T19:04:42.247Z"}}]}}}