libgit2 — security advisory

{
  "id": "7d17eb21d0229a18d40392fcb0043d1884c8dac26d38f0685f8008130bd9ab35",
  "url": "https://osv.dev/vulnerability/DEBIAN-CVE-2026-53587",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "DEBIAN-CVE-2026-53587",
    "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, libgit2 performs a fixed-size strncmp in set_data in src/libgit2/transports/smart_pkt.c without first verifying that the smart-protocol pkt-line capability buffer contains 14 bytes. A malicious Git server can make bytes after the pkt-line complete object-format=, causing format_str to advance beyond the pkt-line and the following memchr length calculation to underflow. The resulting heap out-of-bounds walk can crash a client during the first refs-advertisement packet over HTTP, HTTPS, SSH, or the Git protocol. This issue is fixed in versions 1.8.6 and 1.9.5.",
    "evidence": "osv:DEBIAN-CVE-2026-53587",
    "products": [
      {
        "name": {
          "value": "libgit2",
          "evidence": "/affected/0/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
          {
            "value": "1.9.0+ds-2+deb13u1",
            "evidence": "/affected/0/ranges"
          }
        ],
        "affected_versions": [
          {
            "value": "1.9.0+ds-2",
            "evidence": "/affected/0/versions"
          }
        ]
      },
      {
        "name": {
          "value": "libgit2",
          "evidence": "/affected/1/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
          {
            "value": "1.9.6+ds-1",
            "evidence": "/affected/1/ranges"
          }
        ],
        "affected_versions": [
          {
            "value": "1.9.0+ds-2",
            "evidence": "/affected/1/versions"
          },
          {
            "value": "1.9.1+ds-1",
            "evidence": "/affected/1/versions"
          },
          {
            "value": "1.9.2+ds-1",
            "evidence": "/affected/1/versions"
          },
          {
            "value": "1.9.2+ds-2",
            "evidence": "/affected/1/versions"
          },
          {
            "value": "1.9.2+ds-3",
            "evidence": "/affected/1/versions"
          },
          {
            "value": "1.9.2+ds-4",
            "evidence": "/affected/1/versions"
          },
          {
            "value": "1.9.2+ds-5",
            "evidence": "/affected/1/versions"
          },
          {
            "value": "1.9.2+ds-6",
            "evidence": "/affected/1/versions"
          },
          {
            "value": "1.9.2+ds-7",
            "evidence": "/affected/1/versions"
          },
          {
            "value": "1.9.2+ds-8",
            "evidence": "/affected/1/versions"
          },
          {
            "value": "1.9.2+ds-9",
            "evidence": "/affected/1/versions"
          },
          {
            "value": "1.9.3+ds-1",
            "evidence": "/affected/1/versions"
          },
          {
            "value": "1.9.4+ds-1",
            "evidence": "/affected/1/versions"
          }
        ]
      }
    ],
    "severity": "high",
    "structured": {
      "id": "DEBIAN-CVE-2026-53587",
      "aliases": [
        "DEBIAN-CVE-2026-53587"
      ],
      "metrics": [
        {
          "type": "CVSS_V3",
          "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "0"
                },
                {
                  "fixed": "1.9.0+ds-2+deb13u1"
                }
              ]
            }
          ],
          "package": {
            "name": "libgit2",
            "purl": "pkg:deb/debian/libgit2?arch=source&distro=trixie",
            "ecosystem": "Debian:13"
          },
          "versions": [
            "1.9.0+ds-2"
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2026-53587.json"
          },
          "ecosystem_specific": {
            "urgency": "not yet assigned"
          }
        },
        {
          "ranges": [
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "0"
                },
                {
                  "fixed": "1.9.6+ds-1"
                }
              ]
            }
          ],
          "package": {
            "name": "libgit2",
            "purl": "pkg:deb/debian/libgit2?arch=source&distro=forky",
            "ecosystem": "Debian:14"
          },
          "versions": [
            "1.9.0+ds-2",
            "1.9.1+ds-1",
            "1.9.2+ds-1",
            "1.9.2+ds-2",
            "1.9.2+ds-3",
            "1.9.2+ds-4",
            "1.9.2+ds-5",
            "1.9.2+ds-6",
            "1.9.2+ds-7",
            "1.9.2+ds-8",
            "1.9.2+ds-9",
            "1.9.3+ds-1",
            "1.9.4+ds-1"
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2026-53587.json"
          },
          "ecosystem_specific": {
            "urgency": "not yet assigned"
          }
        }
      ],
      "modified": "2026-10-08T18:00:07.324399639Z",
      "provider": "osv",
      "upstream": [
        "CVE-2026-53587"
      ],
      "references": [
        "https://security-tracker.debian.org/tracker/CVE-2026-53587"
      ]
    },
    "related_cves": [
      {
        "value": "CVE-2026-53587",
        "evidence": "/upstream"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 104427,
  "published_at": "2026-08-20T19:16:55.137+00:00"
}