CVE-2026-39395 PUBLISHED

Cosign's verify-blob-attestation reports false positive when payload parsing fails

Assigner: GitHub_M
Reserved: 06.04.2026 Published: 07.04.2026 Updated: 08.04.2026

Cosign provides code signing and transparency for containers and binaries. Prior to 3.0.6 and 2.6.3, cosign verify-blob-attestation may erroneously report a "Verified OK" result for attestations with malformed payloads or mismatched predicate types. For old-format bundles and detached signatures, this was due to a logic flaw in the error handling of the predicate type validation. For new-format bundles, the predicate type validation was bypassed completely. This vulnerability is fixed in 3.0.6 and 2.6.3.

Metrics

CVSS Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:L/A:N
CVSS Score: 4.3

Product Status

Vendor sigstore
Product cosign
Versions
  • Version >= 3.0.0, < 3.0.6 is affected
  • Version < 2.6.3 is affected

References

Problem Types

  • CWE-754: Improper Check for Unusual or Exceptional Conditions CWE