gitsign — security advisory

{
  "id": "58cb99be9392687052fc51bc06a68c0ff1b5c174b1eb85f26125a8151dacc844",
  "url": "https://osv.dev/vulnerability/UBUNTU-CVE-2026-44309",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "UBUNTU-CVE-2026-44309",
    "summary": "Gitsign is a keyless Sigstore to signing tool for Git commits with your a GitHub / OIDC identity. Prior to 0.16.0, gitsign verify and gitsign verify-tag re-encode commit/tag objects through go-git's EncodeWithoutSignature before checking the signature, instead of verifying against the raw git object bytes. For malformed objects with duplicate tree headers, git-core and go-git parse different trees: git-core uses the first, go-git uses the second. A signature crafted over the go-git-normalized form (second tree) passes gitsign verify while git-core resolves the commit to a completely different tree. This breaks the invariant that a verified signature, the commit semantics git-core presents to users, and the object hash logged in Rekor all refer to the same content. This vulnerability is fixed in 0.16.0.",
    "evidence": "osv:UBUNTU-CVE-2026-44309",
    "products": [
      {
        "name": {
          "value": "gitsign",
          "evidence": "/affected/0/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [],
        "affected_versions": [
          {
            "value": "0.12.0-4",
            "evidence": "/affected/0/versions"
          },
          {
            "value": "0.13.0-1",
            "evidence": "/affected/0/versions"
          },
          {
            "value": "0.13.0-2",
            "evidence": "/affected/0/versions"
          }
        ]
      },
      {
        "name": {
          "value": "gitsign",
          "evidence": "/affected/1/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [],
        "affected_versions": [
          {
            "value": "0.13.0-4",
            "evidence": "/affected/1/versions"
          },
          {
            "value": "0.16.1-2",
            "evidence": "/affected/1/versions"
          },
          {
            "value": "0.16.1-3",
            "evidence": "/affected/1/versions"
          }
        ]
      },
      {
        "name": {
          "value": "gitsign",
          "evidence": "/affected/2/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [],
        "affected_versions": [
          {
            "value": "0.13.0-2",
            "evidence": "/affected/2/versions"
          },
          {
            "value": "0.13.0-3",
            "evidence": "/affected/2/versions"
          },
          {
            "value": "0.13.0-4",
            "evidence": "/affected/2/versions"
          },
          {
            "value": "0.13.0-4ubuntu0.26.04.1~esm1",
            "evidence": "/affected/2/versions"
          }
        ]
      }
    ],
    "severity": "medium",
    "structured": {
      "id": "UBUNTU-CVE-2026-44309",
      "aliases": [
        "UBUNTU-CVE-2026-44309"
      ],
      "metrics": [
        {
          "type": "CVSS_V3",
          "score": "CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:N/I:H/A:N"
        },
        {
          "type": "Ubuntu",
          "score": "medium"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "0"
                }
              ]
            }
          ],
          "package": {
            "name": "gitsign",
            "purl": "pkg:deb/ubuntu/gitsign?arch=source&distro=questing",
            "ecosystem": "Ubuntu:25.10"
          },
          "versions": [
            "0.12.0-4",
            "0.13.0-1",
            "0.13.0-2"
          ],
          "database_specific": {
            "source": "https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-44309.json"
          },
          "ecosystem_specific": {
            "binaries": [
              {
                "binary_name": "gitsign",
                "binary_version": "0.13.0-2"
              },
              {
                "binary_name": "golang-github-sigstore-gitsign-dev",
                "binary_version": "0.13.0-2"
              }
            ]
          }
        },
        {
          "ranges": [
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "0"
                }
              ]
            }
          ],
          "package": {
            "name": "gitsign",
            "purl": "pkg:deb/ubuntu/gitsign?arch=source&distro=stonking",
            "ecosystem": "Ubuntu:26.10"
          },
          "versions": [
            "0.13.0-4",
            "0.16.1-2",
            "0.16.1-3"
          ],
          "database_specific": {
            "source": "https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-44309.json"
          },
          "ecosystem_specific": {
            "binaries": [
              {
                "binary_name": "gitsign",
                "binary_version": "0.16.1-3"
              },
              {
                "binary_name": "golang-github-sigstore-gitsign-dev",
                "binary_version": "0.16.1-3"
              }
            ]
          }
        },
        {
          "ranges": [
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "0"
                }
              ]
            }
          ],
          "package": {
            "name": "gitsign",
            "purl": "pkg:deb/ubuntu/gitsign?arch=source&distro=esm-apps%2Fresolute",
            "ecosystem": "Ubuntu:Pro:26.04:LTS"
          },
          "versions": [
            "0.13.0-2",
            "0.13.0-3",
            "0.13.0-4",
            "0.13.0-4ubuntu0.26.04.1~esm1"
          ],
          "database_specific": {
            "source": "https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-44309.json"
          },
          "ecosystem_specific": {
            "binaries": [
              {
                "binary_name": "gitsign",
                "binary_version": "0.13.0-4ubuntu0.26.04.1~esm1"
              },
              {
                "binary_name": "golang-github-sigstore-gitsign-dev",
                "binary_version": "0.13.0-4ubuntu0.26.04.1~esm1"
              }
            ]
          }
        }
      ],
      "modified": "2026-10-17T12:58:19.437410039Z",
      "provider": "osv",
      "upstream": [
        "CVE-2026-44309"
      ],
      "references": [
        "https://ubuntu.com/security/CVE-2026-44309",
        "https://www.cve.org/CVERecord?id=CVE-2026-44309",
        "https://github.com/sigstore/gitsign/security/advisories/GHSA-7rmh-48mx-2vwc"
      ]
    },
    "related_cves": [
      {
        "value": "CVE-2026-44309",
        "evidence": "/upstream"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 358545,
  "published_at": "2026-05-15T17:16:00+00:00"
}