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.

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Advisories
Source ID Title
Github GHSA Github GHSA GHSA-wfqv-66vq-46rm Cosign considered signatures valid with expired intermediate certificates when transparency log verification is skipped
Fixes

Solution

No solution given by the vendor.


Workaround

No workaround given by the vendor.

History

Fri, 20 Feb 2026 17:15:00 +0000

Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}


Fri, 20 Feb 2026 10:15:00 +0000

Type Values Removed Values Added
First Time appeared Sigstore
Sigstore cosign
Vendors & Products Sigstore
Sigstore cosign

Thu, 19 Feb 2026 22:45:00 +0000

Type Values Removed Values Added
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.
Title Cosign Certificate Chain Expiry Validation Issue Allows Issuing Certificate Expiry to Be Overlooked
Weaknesses CWE-295
References
Metrics cvssV3_1

{'score': 3.7, 'vector': 'CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N'}


Projects

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cve-icon MITRE

Status: PUBLISHED

Assigner: GitHub_M

Published:

Updated: 2026-02-20T15:41:03.939Z

Reserved: 2026-01-21T18:38:22.473Z

Link: CVE-2026-24122

cve-icon Vulnrichment

Updated: 2026-02-20T15:27:30.220Z

cve-icon NVD

Status : Awaiting Analysis

Published: 2026-02-19T23:16:24.517

Modified: 2026-02-20T13:49:47.623

Link: CVE-2026-24122

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

Updated: 2026-02-20T09:53:45Z

Weaknesses