Cosign is a project under the sigstore organization which aims to make signatures invisible infrastructure. In versions prior to 1.12.0 a number of vulnerabilities have been found in cosign verify-blob, where Cosign would successfully verify an artifact when verification should have failed. First a cosign bundle can be crafted to successfully verify a blob even if the embedded rekorBundle does not reference the given signature. Second, when providing identity flags, the email and issuer of a certificate is not checked when verifying a Rekor bundle, and the GitHub Actions identity is never checked. Third, providing an invalid Rekor bundle without the experimental flag results in a successful verification. And fourth an invalid transparency log entry will result in immediate success for verification. Details and examples of these issues can be seen in the GHSA-8gw7-4j42-w388 advisory linked. Users are advised to upgrade to 1.12.0. There are no known workarounds for these issues.
The product does not verify, or incorrectly verifies, the cryptographic signature for data.
| Link | Tags |
|---|---|
| https://github.com/sigstore/cosign/security/advisories/GHSA-8gw7-4j42-w388 | patch exploit mitigation third party advisory |
| https://github.com/sigstore/cosign/commit/80b79ed8b4d28ccbce3d279fd273606b5cddcc25 | third party advisory patch |