CVE-2026-22703
MEDIUM
GHSA-whqx-f9j3-ch6m
CVSS Vector
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:N
Lifecycle Timeline
4Description
Cosign provides code signing and transparency for containers and binaries. Prior to versions 2.6.2 and 3.0.4, Cosign bundle can be crafted to successfully verify an artifact even if the embedded Rekor entry does not reference the artifact's digest, signature or public key. When verifying a Rekor entry, Cosign verifies the Rekor entry signature, and also compares the artifact's digest, the user's public key from either a Fulcio certificate or provided by the user, and the artifact signature to the Rekor entry contents. Without these comparisons, Cosign would accept any response from Rekor as valid. A malicious actor that has compromised a user's identity or signing key could construct a valid Cosign bundle by including any arbitrary Rekor entry, thus preventing the user from being able to audit the signing event. This issue has been patched in versions 2.6.2 and 3.0.4.
Analysis
Cosign's bundle verification mechanism fails to properly validate that embedded Rekor entries reference the correct artifact digest, signature, and public key, allowing an attacker with a compromised signing identity to forge valid bundles and bypass transparency log verification. A malicious actor could exploit this to create counterfeit signatures that pass validation checks, affecting users relying on Cosign for container and binary code signing verification. …
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Remediation
Within 30 days: Identify affected systems and apply vendor patches as part of regular patch cycle. Vendor patch is available.
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External POC / Exploit Code
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