Vulnerabilities in pkg:golang/github.com/sigstore/cosign/v2

{
  "schema_version" : "1.4.0",
  "id" : "GHSA-whqx-f9j3-ch6m",
  "modified" : "2026-01-13T14:58:50Z",
  "published" : "2026-01-13T14:58:50Z",
  "aliases" : [ "CVE-2026-22703" ],
  "summary" : "Cosign verification accepts any valid Rekor entry under certain conditions",
  "details" : "### Impact\n\nA Cosign bundle can be crafted to successfully verify an artifact even if the embedded Rekor entry does not reference the artifact's digest, signature or public key. When verifying a Rekor entry, Cosign verifies the Rekor entry signature, and also compares the artifact's digest, the user's public key from either a Fulcio certificate or provided by the user, and the artifact signature to the Rekor entry contents. Without these comparisons, Cosign would accept any response from Rekor as valid. A malicious actor that has compromised a user's identity or signing key could construct a valid Cosign bundle by including any arbitrary Rekor entry, thus preventing the user from being able to audit the signing event.\n\nThis vulnerability only affects users that provide a trusted root via `--trusted-root` or when fetched automatically from a TUF repository, when no trusted key material is provided via `SIGSTORE_REKOR_PUBLIC_KEY`. When using the default flag values in Cosign v3 to sign and verify (`--use-signing-config=true` and `--new-bundle-format=true` for signing, `--new-bundle-format=true` for verification), users are unaffected. Cosign v2 users are affected using the default flag values.\n\nThis issue had previously been fixed in https://github.com/sigstore/cosign/security/advisories/GHSA-8gw7-4j42-w388 but recent refactoring caused a regression. We have added testing to prevent a future regression.\n\n#### Steps to Reproduce\n\n```\necho blob > /tmp/blob\ncosign sign-blob -y --new-bundle-format=false --bundle /tmp/bundle.1 --use-signing-config=false /tmp/blob\ncosign sign-blob -y --new-bundle-format=false --bundle /tmp/bundle.2 --use-signing-config=false /tmp/blob\njq \".rekorBundle |= $(jq .rekorBundle /tmp/bundle.2)\" /tmp/bundle.1 > /tmp/bundle.3\ncosign verify-blob --bundle /tmp/bundle.3 --certificate-identity-regexp='.*' --certificate-oidc-issuer-regexp='.*' /tmp/blob\n```\n\n### Patches\n\nUpgrade to Cosign v2.6.2 or Cosign v3.0.4. This does not affect Cosign v1.\n\n### Workarounds\n\nYou can provide trusted key material via a set of flags under certain conditions. The simplest fix is to upgrade to the latest Cosign v2 or v3 release.\n\nNote that the example below works for `cosign verify`, `cosign verify-blob, `cosign verify-blob-attestation`, and `cosign verify-attestation`.\n\n```\nSIGSTORE_REKOR_PUBLIC_KEY=<path to Rekor pub key> cosign verify-blob --use-signing-config=false --new-bundle-format=false --bundle=<path to bundle> <artifact>\n```",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:N"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "Go",
      "name" : "github.com/sigstore/cosign/v3"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "3.0.4"
      } ]
    } ],
    "database_specific" : {
      "last_known_affected_version_range" : "<= 3.0.3"
    }
  }, {
    "package" : {
      "ecosystem" : "Go",
      "name" : "github.com/sigstore/cosign/v2"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "2.6.2"
      } ]
    } ],
    "database_specific" : {
      "last_known_affected_version_range" : "<= 2.6.1"
    }
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/sigstore/cosign/security/advisories/GHSA-whqx-f9j3-ch6m"
  }, {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-22703"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/sigstore/cosign/pull/4623"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/sigstore/cosign/commit/6832fba4928c1ad69400235bbc41212de5006176"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/sigstore/cosign"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-345" ],
    "severity" : "MODERATE",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-01-13T14:58:50Z",
    "nvd_published_at" : "2026-01-10T07:16:03Z"
  }
}