{"id":"CVE-2026-53586","state":"PUBLISHED","title":"libgit2: HTTP transport can leak credentials to an offsite redirect target","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, the built-in HTTP transport in src/libgit2/transports/http.c follows an offsite initial redirect, and handle_remote_auth and handle_auth pass transport->owner->url instead of transport->server.url to the credential callback when the redirected host returns 401 Unauthorized. A callback that scopes credentials to the original trusted URL can therefore return GIT_CREDENTIAL_USERPASS_PLAINTEXT credentials that libgit2 stores in transport->server.cred and sends as an Authorization header to the redirected host. An attacker who controls a trusted Git host or an open redirect on that host can disclose HTTP Basic credentials, personal access tokens, or equivalent credentials. This issue is fixed in versions 1.8.6 and 1.9.5.","publishedAt":"2026-08-20T18:40:08.673Z","updatedAt":"2026-08-21T21:46:05.425Z","severity":{"score":6.5,"label":"Medium","version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:N/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-2889-x8f6-mc4x","https://github.com/libgit2/libgit2/commit/07de6a7e438f95ac9a6efd3222a82117e871ed27","https://github.com/libgit2/libgit2/commit/af2b29ad0a74d5bac9751376879ddaf848136d3b","https://github.com/libgit2/libgit2/commit/c1507abc44647b3acd832a33a5b1c8c9f5ba8821","https://github.com/libgit2/libgit2/releases/tag/v1.8.6","https://github.com/libgit2/libgit2/releases/tag/v1.9.5"],"weaknesses":["CWE-200","CWE-522","CWE-601"],"ingestedAt":"2026-10-29T20:12:16.098Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/53xxx/CVE-2026-53586.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-53586","state":"PUBLISHED","datePublished":"2026-08-20T18:40:08.673Z","dateUpdated":"2026-08-21T21:46:05.425Z","assignerShortName":"GitHub_M","assignerOrgId":"a0819718-46f1-4df5-94e2-005712e83aaa","dateReserved":"2026-06-09T19:11:53.484Z"},"containers":{"cna":{"title":"libgit2: HTTP transport can leak credentials to an offsite redirect target","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, the built-in HTTP transport in src/libgit2/transports/http.c follows an offsite initial redirect, and handle_remote_auth and handle_auth pass transport->owner->url instead of transport->server.url to the credential callback when the redirected host returns 401 Unauthorized. A callback that scopes credentials to the original trusted URL can therefore return GIT_CREDENTIAL_USERPASS_PLAINTEXT credentials that libgit2 stores in transport->server.cred and sends as an Authorization header to the redirected host. An attacker who controls a trusted Git host or an open redirect on that host can disclose HTTP Basic credentials, personal access tokens, or equivalent credentials. 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-2889-x8f6-mc4x","name":"https://github.com/libgit2/libgit2/security/advisories/GHSA-2889-x8f6-mc4x","tags":["x_refsource_CONFIRM"]},{"url":"https://github.com/libgit2/libgit2/commit/07de6a7e438f95ac9a6efd3222a82117e871ed27","name":"https://github.com/libgit2/libgit2/commit/07de6a7e438f95ac9a6efd3222a82117e871ed27","tags":["x_refsource_MISC"]},{"url":"https://github.com/libgit2/libgit2/commit/af2b29ad0a74d5bac9751376879ddaf848136d3b","name":"https://github.com/libgit2/libgit2/commit/af2b29ad0a74d5bac9751376879ddaf848136d3b","tags":["x_refsource_MISC"]},{"url":"https://github.com/libgit2/libgit2/commit/c1507abc44647b3acd832a33a5b1c8c9f5ba8821","name":"https://github.com/libgit2/libgit2/commit/c1507abc44647b3acd832a33a5b1c8c9f5ba8821","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":"HIGH","integrityImpact":"NONE","privilegesRequired":"NONE","scope":"UNCHANGED","userInteraction":"REQUIRED","vectorString":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N","version":"3.1"}}],"problemTypes":[{"descriptions":[{"cweId":"CWE-200","lang":"en","description":"CWE-200: Exposure of Sensitive Information to an Unauthorized Actor","type":"CWE"}]},{"descriptions":[{"cweId":"CWE-522","lang":"en","description":"CWE-522: Insufficiently Protected Credentials","type":"CWE"}]},{"descriptions":[{"cweId":"CWE-601","lang":"en","description":"CWE-601: URL Redirection to Untrusted Site ('Open Redirect')","type":"CWE"}]}],"providerMetadata":{"shortName":"GitHub_M","orgId":"a0819718-46f1-4df5-94e2-005712e83aaa","dateUpdated":"2026-08-20T18:40:08.673Z"},"source":{"advisory":"GHSA-2889-x8f6-mc4x","discovery":"UNKNOWN"}},"adp":[{"title":"CISA ADP Vulnrichment","metrics":[{"other":{"type":"ssvc","content":{"timestamp":"2026-08-21T20:58:39.443105Z","id":"CVE-2026-53586","options":[{"Exploitation":"none"},{"Automatable":"no"},{"Technical Impact":"partial"}],"role":"CISA Coordinator","version":"2.0.3"}}}],"providerMetadata":{"shortName":"CISA-ADP","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","dateUpdated":"2026-08-21T21:46:05.425Z"}}]}}}