How severe is CVE-2026-24122?

CVE-2026-24122 has a CVSS score of 3.7/10, rated LOW. Review your exposure and patch according to your risk tolerance.

Which packages are affected by CVE-2026-24122?

CVE-2026-24122 affects the following packages: github.com/sigstore/cosign (Go). Ecosystems affected: Go.

How do I fix CVE-2026-24122?

Update github.com/sigstore/cosign to 3.0.5 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-24122 is resolved across your whole dependency graph.

How do I detect CVE-2026-24122 in my Go dependencies?

Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for github.com/sigstore/cosign, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

How do I mitigate CVE-2026-24122 if there is no patch (or I can't update yet)?

If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.

Is CVE-2026-24122 actively exploited in the wild?

No public exploit code has been indexed for CVE-2026-24122 yet. This does not mean the vulnerability cannot be exploited — absence of public exploits does not imply safety. Apply the recommended fix and use O3 Security to monitor your exposure.

What is the EPSS score for CVE-2026-24122?

CVE-2026-24122 has an EPSS (Exploit Prediction Scoring System) score of 0.2%, placing it in the 12th percentile of all CVEs. EPSS is maintained by FIRST.org and estimates the probability that a vulnerability will be exploited in the wild within the next 30 days. This score indicates relatively lower exploitation probability, though the CVSS severity should still guide your patching priority.

What type of vulnerability is CVE-2026-24122?

CVE-2026-24122 is classified as CWE-295 (CWE-295). This weakness type describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation.

When was CVE-2026-24122 published, and has it been updated?

CVE-2026-24122 was published on February 19, 2026 and was last updated on October 28, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

🐹

🐹 Go

Not in CISA KEV

LOW severity

CVE-2026-24122 — cosign

LOWFix: sigstore/cosign@3c9a736

CVE-2026-24122 is a low-severity (CVSS 3.7) CWE-295 vulnerability in github.com/sigstore/cosign. A fix is available for github.com/sigstore/cosign — see the affected versions and patch details below.

Cosign Certificate Chain Expiry Validation Issue Allows Issuing Certificate Expiry to Be Overlooked

Also known asBIT-cosign-2026-24122GHSA-wfqv-66vq-46rmGO-2026-4529

Published

Feb 19, 2026

Updated

Oct 28, 2026

Affected

1 pkg

Patched

1 / 1

Exploits

None indexed

Exploitation data as of Nov 6, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

Exploitation Status

No confirmed exploitation observed yet

CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.

Exploitation and automatability from CISA’s SSVC triage for CVE-2026-24122.

EPSS Exploitation Probability

via FIRST.org ↗

0.2%probability of exploitation in next 30 days

Lower Risk0.00%

Lower risk than most CVEs12th percentile — riskier than 12% of all scored CVEsHighest risk

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

How urgent is this, really

Where this sits among everything scored

Real-World Exposure

1 pkg affected

🐹github.com/sigstore/cosign

Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects Go packages — download data is not available via public APIs for these ecosystems.

Description

Summary

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.

Impact

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.

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

Affected Packages

1 total 1 fixed

Ecosystem	Package	Vulnerable range	Fix
🐹Go	`github.com/sigstore/cosign`	all versions	3.0.5`go get github.com/sigstore/cosign@v3.0.5`

Affected Products

1 product · 1 configurations

Application

cosignsigstore

< 3.0.5

range

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for github.com/sigstore/cosign, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update github.com/sigstore/cosign to 3.0.5 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-24122 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.

Frequently Asked Questions

## Summary 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 w