Headline
GHSA-vjxv-45g9-9296: cosign's `cosign verify-attestaton --type` can report a false positive if any attestation exists
cosign verify-attestation used with the --type flag will report a false positive verification when:
- There is at least one attestation with a valid signature
- There are NO attestations of the type being verified (–type defaults to “custom”)
This can happen when signing with a standard keypair and with “keyless” signing with Fulcio. Users should upgrade to cosign version 1.10.1 or greater for a patch. Currently the only workaround is to upgrade.
cosign’s `cosign verify-attestaton --type` can report a false positive if any attestation exists
High severity GitHub Reviewed Published Aug 10, 2022 in sigstore/cosign • Updated Aug 10, 2022
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cosign is a container signing and verification utility. In versions prior to 1.10.1 cosign can report a false positive if any attestation exists. `cosign verify-attestation` used with the `--type` flag will report a false positive verification when there is at least one attestation with a valid signature and there are NO attestations of the type being verified (--type defaults to "custom"). This can happen when signing with a standard keypair and with "keyless" signing with Fulcio. This vulnerability can be reproduced with the `distroless.dev/static@sha256:dd7614b5a12bc4d617b223c588b4e0c833402b8f4991fb5702ea83afad1986e2` image. This image has a `vuln` attestation but not an `spdx` attestation. However, if you run `cosign verify-attestation --type=spdx` on this image, it incorrectly succeeds. This issue has been addressed in version 1.10.1 of cosign. Users are advised to upgrade. There are no known workarounds for this issue.