CVE-2026-24122

When verifying artifact signatures using a certificate, Cosign first verifies the certificate chain using the leaf certificate's "not before" timestamp and later checks expiry of the leaf certificate using either a signed timestamp provided by the Rekor transparency log or from a timestamp authority, or using the current time. The root and all issuing certificates are assumed to be valid during the leaf certificate's validity. An issuing certificate with a validity that expires before the leaf certificate will be considered valid during verification even if the provided timestamp would mean the issuing certificate should be considered expired.

Workarounds

Upgrade to the latest release, or verify the certificate chain out of band.

Example to Reproduce

• Root CA certificate is valid from 12pm-2pm
• Intermediate CA certificate is valid from 12:30pm-1:30pm
• Leaf certificate is valid from 1pm-3pm - Note that this is unlikely to happen in practice, as a CA shouldn't issue a certificate that would be valid after the issuing CA certificate expires
• Signature generated at 2:30pm with a signed timestamp
• During verification, the leaf certificate's not before time (1pm) is used to verify the chain - 1pm is in the validity windows for the root and intermediate CA certificates
• The timestamp's time is checked to be in the validity window of only the leaf certificate - 2:30pm is in the validity window for the leaf
• Even though the root and intermediate would be expired at 2:30pm, verification succeeds

No impact to users of the public Sigstore infrastructure. This may affect private deployments with customized PKIs. In practice, this is unlikely to occur as CAs should not be issuing certificates that outlive the validity of the CA and its parents.

CVE-2026-24122 has a CVSS score of 3.7 (Low). The vector is network-reachable, no privileges required, and no user interaction. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (3.0.5); upgrading removes the vulnerable code path.

Kodem intelligence

1. What is CVE-2026-24122? CVE-2026-24122 is a low-severity security vulnerability in github.com/sigstore/cosign (go), affecting versions <= 3.0.4. It is fixed in 3.0.5.
2. How severe is CVE-2026-24122? CVE-2026-24122 has a CVSS score of 3.7 (Low). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
3. Which versions of github.com/sigstore/cosign are affected by CVE-2026-24122? github.com/sigstore/cosign (go) versions <= 3.0.4 is affected.
4. Is there a fix for CVE-2026-24122? Yes. CVE-2026-24122 is fixed in 3.0.5. Upgrade to this version or later.
5. Is CVE-2026-24122 exploitable, and should I be worried? Whether CVE-2026-24122 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
6. What actually determines whether CVE-2026-24122 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
7. How do I fix CVE-2026-24122? Upgrade github.com/sigstore/cosign to 3.0.5 or later.