Bug 2116258 (CVE-2022-35929)

Summary:	CVE-2022-35929 cosign: `cosign verify-attestation --type` can report a false positive if any attestation exists
Product:	[Other] Security Response	Reporter:	Avinash Hanwate <ahanwate>
Component:	vulnerability	Assignee:	Nobody <nobody>
Status:	NEW ---	QA Contact:
Severity:	medium	Docs Contact:
Priority:	medium
Version:	unspecified	CC:	bmontgom, eparis, jburrell, jwon, lball, matzew, nstielau, rhuss, sponnaga, vkumar
Target Milestone:	---	Keywords:	Security
Target Release:	---
Hardware:	All
OS:	Linux
Whiteboard:
Fixed In Version:	cosign 1.10.1	Doc Type:	If docs needed, set a value
Doc Text:	A flaw was found in the cosign package. The 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 when there are no attestations of the type being verified (for example, —type defaults to "custom"). This issue can happen when signing with a standard keypair and keyless signing with Fulcio.	Story Points:	---
Clone Of:		Environment:
Last Closed:		Type:	---
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Documentation:	---	CRM:
Verified Versions:		Category:	---
oVirt Team:	---	RHEL 7.3 requirements from Atomic Host:
Cloudforms Team:	---	Target Upstream Version:
Embargoed:
Bug Depends On:	2116259
Bug Blocks:	2115623

Description Avinash Hanwate 2022-08-08 04:33:30 UTC

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.

https://github.com/sigstore/cosign/commit/c5fda01a8ff33ca981f45a9f13e7fb6bd2080b94
https://github.com/sigstore/cosign/security/advisories/GHSA-vjxv-45g9-9296