Cosign Certificate Chain Expiry Validation Issue Allows Issuing Certificate Expiry to Be Overlooked (sigstore cosign)
At a glance
- Source
- NVD
- EPSS
- EPSS 0.21 % · percentile 12 ()
- State
- PUBLISHED
- Published
- Updated
- Assigner
- GitHub_M
- NVD status
- Analyzed
Description
Cosign provides code signing and transparency for containers and binaries. In versions 3.0.4 and below, 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. 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. There is no impact to users of the public Sigstore infrastructure. This may affect private deployments with customized PKIs. This issue has been fixed in version 3.0.5.
Weaknesses (CWE)
- CWE-295 — Improper Certificate Validation
References
Scores
| Version | Score | Vector | Scored by |
|---|---|---|---|
| CVSS 3.1 | LOW 3.7 | CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N | GitHub_M |
| CVSS 3.1 | LOW 3.7 | CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N | NVD · security-advisories@github.com (Secondary) |
Advisories
- GHSA-wfqv-66vq-46rm — Cosign considered signatures valid with expired intermediate certificates when transparency log verification is skipped
- GO-2026-4529 — Cosign considered signatures valid with expired intermediate certificates when transparency log verification is skipped in github.com/sigstore/cosign
European references
- ENISA EUVD · EUVD-2026-8430
- GCVE · GCVE-0-2026-24122
CERT-FR advisories
- CERTFR-2026-AVI-1385 — Multiples vulnérabilités dans les produits VMware · cert.ssi.gouv.fr
Affected configurations (NVD CPE)
cpe:2.3:a:sigstore:cosign:*:*:*:*:*:*:*:*< 3.0.5
Affected products
| Product | Versions |
|---|---|
| sigstore · cosign | affected < 3.0.5 |
Sources
| Source | Licence |
|---|---|
| CVE List (CVEProject cvelistV5) | CVE Program Terms of Use |
| EPSS (FIRST.org) | FIRST — attribution requested |
| ENISA EUVD | ENISA — reproduction authorised, source acknowledged |
| CERT-FR (ANSSI) | Licence Ouverte / Etalab 2.0 |
| NVD (NIST) via fkie-cad/nvd-json-data-feeds | Public domain — this product uses data from the NVD API but is not endorsed or certified by the NVD |