sigstore cosign up to 2.6.1/3.0.3 data authenticity

Summaryinfo

A vulnerability identified as problematic has been detected in sigstore cosign up to 2.6.1/3.0.3. This affects an unknown part. Performing a manipulation results in data authenticity. This vulnerability is cataloged as CVE-2026-22703. The attack must be initiated from a local position. There is no exploit available. You should upgrade the affected component.

Detailsinfo

A vulnerability, which was classified as problematic, was found in sigstore cosign up to 2.6.1/3.0.3. This affects some unknown functionality. The manipulation with an unknown input leads to a data authenticity vulnerability. CWE is classifying the issue as CWE-345. The product does not sufficiently verify the origin or authenticity of data, in a way that causes it to accept invalid data. This is going to have an impact on integrity. The summary by CVE is:

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.

It is possible to read the advisory at github.com. This vulnerability is uniquely identified as CVE-2026-22703 since 01/08/2026. The exploitability is told to be easy. Attacking locally is a requirement. The technical details are unknown and an exploit is not publicly available.

The vulnerability scanner Nessus provides a plugin with the ID 282559 (Linux Distros Unpatched Vulnerability : CVE-2026-22703), which helps to determine the existence of the flaw in a target environment.

Upgrading to version 2.6.2 or 3.0.4 eliminates this vulnerability. Applying the patch 6832fba4928c1ad69400235bbc41212de5006176 is able to eliminate this problem. The bugfix is ready for download at github.com. The best possible mitigation is suggested to be upgrading to the latest version.

The vulnerability is also documented in the databases at Tenable (282559) and EUVD (EUVD-2026-1868). Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.

Productinfo

Vendor

• sigstore

Name

• cosign

Version

• 2.6.0
• 2.6.1
• 3.0.0
• 3.0.1
• 3.0.2
• 3.0.3

License

• open-source

Website

• Product: https://github.com/sigstore/cosign/

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