Description

Cosign provides code signing and transparency for containers and binaries. Prior to versions 2.6.2 and 3.0.4, 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. This issue has been patched in versions 2.6.2 and 3.0.4.

Weaknesses 1

Affected Products 2

References 3

• github.com https://github.com/sigstore/cosign/commit/6832fba4928c1ad69400235bbc41212de5006176
  Patch
• github.com https://github.com/sigstore/cosign/pull/4623
  Issue Tracking
• github.com https://github.com/sigstore/cosign/security/advisories/GHSA-whqx-f9j3-ch6m
  ExploitVendor Advisory

Remediation

• github.com https://github.com/sigstore/cosign/commit/6832fba4928c1ad69400235bbc41212de5006176
  Patch