CVE-2026-49834

MEDIUM 5.9

sigstore-go: Multi-log threshold bypass via single compromised log

CVSS Score

5.9

EPSS Score

0.0%

EPSS Percentile

0th

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.

CWE	CWE-347
Vendor	sigstore
Product	sigstore-go
Published	Jul 17, 2026
Last Updated	Jul 17, 2026

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CVSS v3 Breakdown

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:N

Attack Vector

Network

Attack Complexity

High

Privileges Required

None

User Interaction

None

Scope

Unchanged

Confidentiality

None

Integrity

High

Availability

None

Affected Versions

sigstore / sigstore-go

< 1.2.0

References

NVD ↗ CVE.org ↗ EPSS Data ↗

github.com: https://github.com/sigstore/sigstore-go/security/advisories/GHSA-9vcr-p3rj-q5q6 github.com: https://github.com/sigstore/sigstore-go/pull/633 github.com: https://github.com/sigstore/sigstore-go/commit/dbb07e62623edd5b175fb9dd5a41dcb85a159207 github.com: https://github.com/sigstore/sigstore-go/releases/tag/v1.2.0