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MEDIUM4.3

GHSA-w6c6-c85g-mmv6

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

Quick fix

GHSA-w6c6-c85g-mmv6 — github.com/sigstore/cosign: upgrade to the fixed version with the command below.

go get github.com/sigstore/cosign@v3.0.6

Details

## Description

`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.

## Impact

When `cosign verify-blob-attestation` is used without `--check-claims` set to `true`, an attestation that has a valid signature but a malformed or unparsable payload would be incorrectly validated. Additionally, systems relying on `--type <predicate type>` to reject attestations with mismatched types would be lead to trust the unexpected attestation type.

## Patches

v3.0.6, v2.6.3

## Workarounds

Always set `--check-claims=true` for attestation verification.

Are you affected?

Enter the version of the package you're using.

Affected packages

Go/github.com/sigstore/cosign
Introduced in: 3.0.0Fixed in: 3.0.6
Fixgo get github.com/sigstore/cosign@v3.0.6
Go/github.com/sigstore/cosign
Introduced in: 0Fixed in: 2.6.3
Fixgo get github.com/sigstore/cosign@v2.6.3

References