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

4.3 / 10

MEDIUM

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

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.

Basic Information

ID CVE-2026-39395

Source GitHub_M

Published Apr 7, 2026 at 20:06

Modified Apr 8, 2026 at 15:49

Affected Product

Vendor sigstore

Product cosign

Version >= 3.0.0, < 3.0.6

Affected Versions sigstore cosign >= 3.0.0, < 3.0.6
sigstore cosign < 2.6.3

CWE Classification

CWE-754

References

github.com /sigstore/cosign/security/advisories/GHSA-w6c6-c85g-mmv6

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Cosign’s verify-blob-attestation reports false positive when payload parsing fails_CVE-2026-39395