CVE-2026-53586 (GCVE-0-2026-53586)

Vulnerability from cvelistv5 – Published: 2026-08-20 18:40 – Updated: 2026-08-20 18:40
VLAI
Title
libgit2: HTTP transport can leak credentials to an offsite redirect target
Summary
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.
Severity
6.5 (Medium)
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N
CWE
  • CWE-200 - Exposure of Sensitive Information to an Unauthorized Actor
  • CWE-522 - Insufficiently Protected Credentials
  • CWE-601 - URL Redirection to Untrusted Site ('Open Redirect')
Assigner
References
Impacted products
Vendor Product Version CPE status
libgit2 libgit2 Affected: < 1.8.6
Affected: >= 1.9.0, < 1.9.5
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{
  "containers": {
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        {
          "product": "libgit2",
          "vendor": "libgit2",
          "versions": [
            {
              "status": "affected",
              "version": "\u003c 1.8.6"
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        }
      ],
      "metrics": [
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            "availabilityImpact": "NONE",
            "baseScore": 6.5,
            "baseSeverity": "MEDIUM",
            "confidentialityImpact": "HIGH",
            "integrityImpact": "NONE",
            "privilegesRequired": "NONE",
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            "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N",
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        },
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          "url": "https://github.com/libgit2/libgit2/commit/07de6a7e438f95ac9a6efd3222a82117e871ed27"
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        },
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        },
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          "name": "https://github.com/libgit2/libgit2/releases/tag/v1.8.6",
          "tags": [
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          "url": "https://github.com/libgit2/libgit2/releases/tag/v1.8.6"
        },
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          "tags": [
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          "url": "https://github.com/libgit2/libgit2/releases/tag/v1.9.5"
        }
      ],
      "source": {
        "advisory": "GHSA-2889-x8f6-mc4x",
        "discovery": "UNKNOWN"
      },
      "title": "libgit2: HTTP transport can leak credentials to an offsite redirect target"
    }
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    "assignerShortName": "GitHub_M",
    "cveId": "CVE-2026-53586",
    "datePublished": "2026-08-20T18:40:08.673Z",
    "dateReserved": "2026-06-09T19:11:53.484Z",
    "dateUpdated": "2026-08-20T18:40:08.673Z",
    "state": "PUBLISHED"
  },
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  "vulnerability-lookup:meta": {
    "epss": {
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      "date": "2026-08-21",
      "epss": "0.00469",
      "percentile": "0.38908"
    },
    "nvd": "{\"cve\":{\"id\":\"CVE-2026-53586\",\"sourceIdentifier\":\"security-advisories@github.com\",\"published\":\"2026-08-20T19:16:54.983\",\"lastModified\":\"2026-08-20T19:16:54.983\",\"vulnStatus\":\"Received\",\"cveTags\":[],\"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-\u003eowner-\u003eurl instead of transport-\u003eserver.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-\u003eserver.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\":[{\"source\":\"security-advisories@github.com\",\"affectedData\":[{\"vendor\":\"libgit2\",\"product\":\"libgit2\",\"versions\":[{\"version\":\"\u003c 1.8.6\",\"status\":\"affected\"},{\"version\":\"\u003e= 1.9.0, \u003c 1.9.5\",\"status\":\"affected\"}]}]}],\"metrics\":{\"cvssMetricV31\":[{\"source\":\"security-advisories@github.com\",\"type\":\"Secondary\",\"cvssData\":{\"version\":\"3.1\",\"vectorString\":\"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N\",\"baseScore\":6.5,\"baseSeverity\":\"MEDIUM\",\"attackVector\":\"NETWORK\",\"attackComplexity\":\"LOW\",\"privilegesRequired\":\"NONE\",\"userInteraction\":\"REQUIRED\",\"scope\":\"UNCHANGED\",\"confidentialityImpact\":\"HIGH\",\"integrityImpact\":\"NONE\",\"availabilityImpact\":\"NONE\"},\"exploitabilityScore\":2.8,\"impactScore\":3.6}]},\"weaknesses\":[{\"source\":\"security-advisories@github.com\",\"type\":\"Primary\",\"description\":[{\"lang\":\"en\",\"value\":\"CWE-200\"},{\"lang\":\"en\",\"value\":\"CWE-522\"},{\"lang\":\"en\",\"value\":\"CWE-601\"}]}],\"references\":[{\"url\":\"https://github.com/libgit2/libgit2/commit/07de6a7e438f95ac9a6efd3222a82117e871ed27\",\"source\":\"security-advisories@github.com\"},{\"url\":\"https://github.com/libgit2/libgit2/commit/af2b29ad0a74d5bac9751376879ddaf848136d3b\",\"source\":\"security-advisories@github.com\"},{\"url\":\"https://github.com/libgit2/libgit2/commit/c1507abc44647b3acd832a33a5b1c8c9f5ba8821\",\"source\":\"security-advisories@github.com\"},{\"url\":\"https://github.com/libgit2/libgit2/releases/tag/v1.8.6\",\"source\":\"security-advisories@github.com\"},{\"url\":\"https://github.com/libgit2/libgit2/releases/tag/v1.9.5\",\"source\":\"security-advisories@github.com\"},{\"url\":\"https://github.com/libgit2/libgit2/security/advisories/GHSA-2889-x8f6-mc4x\",\"source\":\"security-advisories@github.com\"}]}}"
  }
}



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Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.

Sightings

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Nomenclature

  • Seen: The vulnerability was mentioned, discussed, or observed by the user.
  • Confirmed: The vulnerability has been validated from an analyst's perspective.
  • Published Proof of Concept: A public proof of concept is available for this vulnerability.
  • Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
  • Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
  • Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
  • Not confirmed: The user expressed doubt about the validity of the vulnerability.
  • Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.


Detection rules are retrieved from Rulezet.