golang-github-sigstore-fulcio — security advisory

{
  "id": "a6d4eb8d3e8ad64bccf883a6d392e2cc5822006ab2b9ece835b40b49e012e249",
  "url": "https://osv.dev/vulnerability/UBUNTU-CVE-2025-66506",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "UBUNTU-CVE-2025-66506",
    "summary": "Fulcio is a free-to-use certificate authority for issuing code signing certificates for an OpenID Connect (OIDC) identity. Prior to 1.8.3, function identity.extractIssuerURL splits (via a call to strings.Split) its argument (which is untrusted data) on periods. As a result, in the face of a malicious request with an (invalid) OIDC identity token in the payload containing many period characters, a call to extractIssuerURL incurs allocations to the tune of O(n) bytes (where n stands for the length of the function's argument), with a constant factor of about 16. This vulnerability is fixed in 1.8.3.",
    "evidence": "osv:UBUNTU-CVE-2025-66506",
    "products": [
      {
        "name": {
          "value": "golang-github-sigstore-fulcio",
          "evidence": "/affected/0/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [],
        "affected_versions": [
          {
            "value": "1.6.5-1",
            "evidence": "/affected/0/versions"
          }
        ]
      },
      {
        "name": {
          "value": "golang-github-sigstore-fulcio",
          "evidence": "/affected/1/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [],
        "affected_versions": [
          {
            "value": "1.7.1-1",
            "evidence": "/affected/1/versions"
          },
          {
            "value": "1.8.7-1",
            "evidence": "/affected/1/versions"
          },
          {
            "value": "1.8.8-1",
            "evidence": "/affected/1/versions"
          }
        ]
      },
      {
        "name": {
          "value": "golang-github-sigstore-fulcio",
          "evidence": "/affected/2/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [],
        "affected_versions": [
          {
            "value": "1.6.5-1",
            "evidence": "/affected/2/versions"
          },
          {
            "value": "1.7.1-1",
            "evidence": "/affected/2/versions"
          }
        ]
      }
    ],
    "severity": "high",
    "structured": {
      "id": "UBUNTU-CVE-2025-66506",
      "aliases": [
        "UBUNTU-CVE-2025-66506"
      ],
      "metrics": [
        {
          "type": "CVSS_V3",
          "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H"
        },
        {
          "type": "Ubuntu",
          "score": "medium"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "0"
                }
              ]
            }
          ],
          "package": {
            "name": "golang-github-sigstore-fulcio",
            "purl": "pkg:deb/ubuntu/golang-github-sigstore-fulcio?arch=source&distro=questing",
            "ecosystem": "Ubuntu:25.10"
          },
          "versions": [
            "1.6.5-1"
          ],
          "database_specific": {
            "source": "https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2025/UBUNTU-CVE-2025-66506.json"
          },
          "ecosystem_specific": {
            "binaries": [
              {
                "binary_name": "golang-github-sigstore-fulcio-dev",
                "binary_version": "1.6.5-1"
              }
            ]
          }
        },
        {
          "ranges": [
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "0"
                }
              ]
            }
          ],
          "package": {
            "name": "golang-github-sigstore-fulcio",
            "purl": "pkg:deb/ubuntu/golang-github-sigstore-fulcio?arch=source&distro=stonking",
            "ecosystem": "Ubuntu:26.10"
          },
          "versions": [
            "1.7.1-1",
            "1.8.7-1",
            "1.8.8-1"
          ],
          "database_specific": {
            "source": "https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2025/UBUNTU-CVE-2025-66506.json"
          },
          "ecosystem_specific": {
            "binaries": [
              {
                "binary_name": "golang-github-sigstore-fulcio-dev",
                "binary_version": "1.8.8-1"
              }
            ]
          }
        },
        {
          "ranges": [
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "0"
                }
              ]
            }
          ],
          "package": {
            "name": "golang-github-sigstore-fulcio",
            "purl": "pkg:deb/ubuntu/golang-github-sigstore-fulcio?arch=source&distro=resolute",
            "ecosystem": "Ubuntu:26.04:LTS"
          },
          "versions": [
            "1.6.5-1",
            "1.7.1-1"
          ],
          "database_specific": {
            "source": "https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2025/UBUNTU-CVE-2025-66506.json"
          },
          "ecosystem_specific": {
            "binaries": [
              {
                "binary_name": "golang-github-sigstore-fulcio-dev",
                "binary_version": "1.7.1-1"
              }
            ]
          }
        }
      ],
      "modified": "2026-10-17T12:57:38.166413377Z",
      "provider": "osv",
      "upstream": [
        "CVE-2025-66506"
      ],
      "references": [
        "https://ubuntu.com/security/CVE-2025-66506",
        "https://www.cve.org/CVERecord?id=CVE-2025-66506",
        "https://github.com/sigstore/fulcio/commit/765a0e57608b9ef390e1eeeea8595b9054c63a5a",
        "https://github.com/sigstore/fulcio/security/advisories/GHSA-f83f-xpx7-ffpw"
      ]
    },
    "related_cves": [
      {
        "value": "CVE-2025-66506",
        "evidence": "/upstream"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 357656,
  "published_at": "2025-12-04T22:15:00+00:00"
}