AVID-2026-R1115

Description

Vulnerabilities with blob verification in sigstore cosign (CVE-2022-36056)

Details

Cosign is a project under the sigstore organization which aims to make signatures invisible infrastructure. In versions prior to 1.12.0 a number of vulnerabilities have been found in cosign verify-blob, where Cosign would successfully verify an artifact when verification should have failed. First a cosign bundle can be crafted to successfully verify a blob even if the embedded rekorBundle does not reference the given signature. Second, when providing identity flags, the email and issuer of a certificate is not checked when verifying a Rekor bundle, and the GitHub Actions identity is never checked. Third, providing an invalid Rekor bundle without the experimental flag results in a successful verification. And fourth an invalid transparency log entry will result in immediate success for verification. Details and examples of these issues can be seen in the GHSA-8gw7-4j42-w388 advisory linked. Users are advised to upgrade to 1.12.0. There are no known workarounds for these issues.

Reason for inclusion in AVID: CVE-2022-36056 describes multiple flaws in cosign’s blob verification (sigstore) that can cause invalid artifacts to pass verification, enabling potential tampering in artifact signing/verification workflows. Cosign is a software supply-chain tool used to sign and verify artifacts (e.g., container images, model artifacts) in AI system build/deploy pipelines. This is a software/CI-CD/tooling vulnerability with direct impact on AI pipelines, hence relevant to the general-purpose AI supply chain. Evidence included: advisory mentions version fix and CVE/CWE-347.

References

Affected or Relevant Artifacts

Developer: sigstore
Deployer: sigstore
Artifact Details:

Type	Name
System	cosign

Impact

AVID Taxonomy Categorization

Risk domains: Security
SEP subcategories: S0100: Software Vulnerability
Lifecycle stages: L06: Deployment

CVSS

Version	3.1
Vector String	CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:N
Base Score	5.5
Base Severity	🟠 Medium
Attack Vector	LOCAL
Attack Complexity	🟢 Low
Privileges Required	🟢 Low
User Interaction	NONE
Scope	UNCHANGED
Confidentiality Impact	NONE
Integrity Impact	🔴 High
Availability Impact	NONE

CWE

ID	Description
CWE-347	CWE-347: Improper Verification of Cryptographic Signature

Other information

Report Type: Advisory
Credits:
Date Reported: 2022-09-14
Version: 0.3.3
AVID Entry