CVE-2026-39395
MEDIUM4.3EPSS 0.04%Cosign's verify-blob-attestation reports false positive when payload parsing fails
Published: 4/8/2026Modified: 4/17/2026
Description
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.
Affected packages (4)
- Bitnami/cosignfrom 0, < 2.6.3, >= 3.0.0, < 3.0.6
- Debian/cosignfrom 0
- Debian/golang-github-sigstore-cosign-v2from 0, < 2.6.3-2
- Go/github.com/sigstore/cosign>= 3.0.0, < 3.0.6
CVSS scores
| Source | Version | Severity | Vector |
|---|---|---|---|
| osv | CVSS 3.1 | MEDIUM4.3 | CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:L/A:N |