CVE-2026-22703

Описание

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.

A data verification flaw has been discovered in the golang cosign library. A 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 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.