UBUNTU-CVE-2026-53587 (CVE-2026-53587)

Vulnerability from osv_ubuntu – Published: 2026-07-31 00:00 – Updated: 2026-09-02 16:20 – Source website
VLAI
Details

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.

Severity
7.5 (High)
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
N/A (UNKNOWN)
medium
References
To clipboard 

{
  "affected": [
    {
      "ecosystem_specific": {
        "availability": "No subscription required",
        "binaries": [
          {
            "binary_name": "libgit2-1.7",
            "binary_version": "1.7.2+ds-1ubuntu3.1"
          },
          {
            "binary_name": "libgit2-fixtures",
            "binary_version": "1.7.2+ds-1ubuntu3.1"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:24.04:LTS",
        "name": "libgit2",
        "purl": "pkg:deb/ubuntu/libgit2@1.7.2+ds-1ubuntu3.1?arch=source\u0026distro=noble"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "1.7.2+ds-1ubuntu3.1"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "1.5.1+ds-1ubuntu1",
        "1.7.1+ds-2ubuntu1",
        "1.7.2+ds-1ubuntu1",
        "1.7.2+ds-1ubuntu2",
        "1.7.2+ds-1ubuntu3"
      ]
    },
    {
      "ecosystem_specific": {
        "availability": "No subscription required",
        "binaries": [
          {
            "binary_name": "libgit2-1.9",
            "binary_version": "1.9.1+ds-1ubuntu1.1"
          },
          {
            "binary_name": "libgit2-fixtures",
            "binary_version": "1.9.1+ds-1ubuntu1.1"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:26.04:LTS",
        "name": "libgit2",
        "purl": "pkg:deb/ubuntu/libgit2@1.9.1+ds-1ubuntu1.1?arch=source\u0026distro=resolute"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "1.9.1+ds-1ubuntu1.1"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "1.9.0+ds-2ubuntu2",
        "1.9.1+ds-1ubuntu1"
      ]
    }
  ],
  "aliases": [],
  "details": "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.",
  "id": "UBUNTU-CVE-2026-53587",
  "modified": "2026-09-02T16:20:00Z",
  "published": "2026-07-31T00:00:00Z",
  "references": [
    {
      "type": "REPORT",
      "url": "https://ubuntu.com/security/CVE-2026-53587"
    },
    {
      "type": "REPORT",
      "url": "https://www.cve.org/CVERecord?id=CVE-2026-53587"
    },
    {
      "type": "REPORT",
      "url": "https://github.com/libgit2/libgit2/security/advisories/GHSA-pm24-4jhq-3xvm"
    },
    {
      "type": "ADVISORY",
      "url": "https://ubuntu.com/security/notices/USN-8628-1"
    }
  ],
  "related": [
    "USN-8628-1"
  ],
  "schema_version": "1.7.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
      "type": "CVSS_V3"
    },
    {
      "score": "medium",
      "type": "Ubuntu"
    }
  ],
  "upstream": [
    "CVE-2026-53587"
  ]
}



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