CVE-2026-39395
Cosign's verify-blob-attestation reports false positive when payload parsing fails
CVSS Score
4.3
EPSS Score
0.0%
EPSS Percentile
8th
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.
| CWE | CWE-754 |
| Vendor | sigstore |
| Product | cosign |
| Published | Apr 7, 2026 |
| Last Updated | Apr 8, 2026 |
Stay Ahead of the Next One
Get instant alerts for sigstore cosign
Be the first to know when new medium vulnerabilities affecting sigstore cosign are published — delivered to Slack, Telegram or Discord.
Get Free Alerts →
Free · No credit card · 60 sec setup
CVSS v3 Breakdown
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:L/A:N Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
Required
Scope
Unchanged
Confidentiality
None
Integrity
Low
Availability
None
Affected Versions
sigstore / cosign
>= 3.0.0, < 3.0.6 < 2.6.3