CVE-2026-39395
Cosign's verify-blob-attestation reports false positive when payload parsing fails
4.3CVSSMEDIUM
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.
CVSS Vector Breakdown
Exploitability
AV:NAttack VectorNetwork
AC:LAttack ComplexityLow
PR:NPrivileges RequiredNone
UI:RUser InteractionRequired
Scope
S:UScopeUnchanged
Impact
C:NConfidentialityNone
I:LIntegrityLow
A:NAvailabilityNone
Weaknesses
Affected Products
Exploitability
Workaround Available
References
Timeline
Published
Apr 7, 2026
Last Updated
Apr 15, 2026
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