Bug 2441194 (CVE-2026-24122)

Summary:	CVE-2026-24122 sigstore/cosign: sigstore/cosign: Incorrect signature validation due to expired issuing certificate bypass
Product:	[Other] Security Response	Reporter:	OSIDB Bzimport <bzimport>
Component:	vulnerability	Assignee:	Product Security DevOps Team <prodsec-dev>
Status:	NEW ---	QA Contact:
Severity:	low	Docs Contact:
Priority:	low
Version:	unspecified	CC:	agarcial, akoudelk, alcohan, anthomas, aoconnor, aprice, asegurap, caswilli, dhanak, drosa, dsimansk, ehelms, ggainey, gparvin, jbalunas, jburrell, jdobes, jkoehler, jsamir, juwatts, kaycoth, kingland, kverlaen, lball, lbragsta, lphiri, mhulan, mnovotny, mstipich, ngough, nmoumoul, oezr, orabin, osousa, pahickey, pcreech, rchan, rexwhite, rhaigner, sausingh, smallamp, sthirugn, tmalecek, veshanka, wenshen, xiyuan
Target Milestone:	---	Keywords:	Security
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Hardware:	All
OS:	Linux
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Doc Text:	A flaw was found in sigstore/cosign. This vulnerability affects private deployments using customized Public Key Infrastructures (PKIs), where it can lead to incorrect validation of artifact signatures. Cosign may mistakenly accept an issuing certificate as valid even if its expiration date precedes the leaf certificate's, potentially allowing invalid signatures to be trusted. This could compromise the integrity of signature verification in affected environments.	Story Points:	---
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oVirt Team:	---	RHEL 7.3 requirements from Atomic Host:
Cloudforms Team:	---	Target Upstream Version:
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Description OSIDB Bzimport 2026-02-19 23:02:10 UTC

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.