---
id: CVE-2026-49834
aliases:
  - GHSA-9vcr-p3rj-q5q6
title: sigstore-go has a multi-log threshold bypass via single compromised log
summary: sigstore-go has a multi-log threshold bypass via single compromised log
severity: medium
cvss: 5.9
cwe:
  - CWE-345
vendor: sigstore
product: github.com/sigstore/sigstore-go
ecosystem: go
affected:
  - github.com/sigstore/sigstore-go <= 1.1.4
patched:
  - github.com/sigstore/sigstore-go 1.2.0
published: '2026-07-09'
updated: '2026-07-09'
source: GHSA
sourceUrl: 'https://github.com/advisories/GHSA-9vcr-p3rj-q5q6'
references:
  - url: >-
      https://github.com/sigstore/sigstore-go/security/advisories/GHSA-9vcr-p3rj-q5q6
  - url: 'https://github.com/advisories/GHSA-9vcr-p3rj-q5q6'
tags:
  - ghsa
  - go
ingestedAt: '2026-07-09T23:53:27.219Z'
---

## Overview

### Impact
_What kind of vulnerability is it? Who is impacted?_

A verifier configured with WithTransparencyLog(N>1) or WithSignedCertificateTimestamps(N>1) expected defense-in-depth against the compromise of a single log instance. However, threshold counting counted verified witnesses per-entry or per-validation-path rather than per-log-authority.

As a result, a single compromised transparency log could forge multiple entries with different indices, and a single compromised CT log could verify multiple times (either across multiple certificate chains or via multiple embedded SCTs), fully satisfying the multi-log threshold requirements and defeating the multi-log policy.

Note that this does not affect Cosign, as Cosign sets a threshold of 1.

### Patches
_Has the problem been patched? What versions should users upgrade to?_

Upgrade to v1.1.5.

### Workarounds
_Is there a way for users to fix or remediate the vulnerability without upgrading?_

There is no workaround, beyond relying on trusted logs.

## Affected packages

- `github.com/sigstore/sigstore-go <= 1.1.4`

## Remediation

Upgrade to a patched release:

- `github.com/sigstore/sigstore-go 1.2.0`