Bug 2501871 (CVE-2026-49834)

Summary: CVE-2026-49834 github.com/sigstore/sigstore-go: sigstore-go: Security Policy Bypass via Compromised Log
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security <prodsec-ir-bot>
Status: NEW --- QA Contact:
Severity: medium Docs Contact:
Priority: medium    
Version: unspecifiedCC: akoudelk, cahl, dfreiber, drow, eborisov, gbenhaim, jburrell, lball, lbragsta, ljawale, msilmser, ngough, niyer, sdawley, teagle, twaugh, veshanka, vkumar, wenshen
Target Milestone: ---Keywords: Security
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Hardware: All   
OS: Linux   
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A flaw was found in sigstore-go, a Go library for Sigstore signing and verification. This vulnerability allows a single compromised transparency log or Certificate Transparency (CT) log to bypass the multi-log threshold requirements. An attacker could exploit this by compromising a single log, thereby defeating the intended security policy and potentially compromising the integrity of the verification process.
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oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: --- Target Upstream Version:
Embargoed:
Bug Depends On: 2513977, 2513981, 2513984, 2513978, 2513979, 2513980, 2513982, 2513983    
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Description OSIDB Bzimport 2026-07-17 20:01:33 UTC
sigstore-go is a Go library for Sigstore signing and verification. Prior to 1.2.0, a verifier configured with WithTransparencyLog(N>1) or WithSignedCertificateTimestamps(N>1) counts verified witnesses per entry or per validation path rather than per log authority, allowing a single compromised transparency log or CT log to satisfy multi-log threshold requirements and defeat the multi-log policy. This issue is fixed in version 1.2.0.