🛡️ CVE-2026-49834 — sigstore-go

🟡 CVSS 5.9 — Medium ✅ No Known Exploit CWE-345 NVD
5.9
CVSS Score
0 Low4 Medium7 High9 Critical10

Description

sigstore-go has a multi-log threshold bypass via single compromised log

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.

How this vulnerability can be exploited

This issue can be reached over the network, attack complexity is high, an attacker needs no privileges on the target. No user interaction is required. The scope is unchanged, so the impact stays within the vulnerable component. Rated impact: confidentiality none, integrity high, availability none.

Weakness class

CVE-2026-49834 is classified as CWE-345: Insufficient Verification of Data Authenticity. Data is trusted without confirming it really came from the claimed source and was not altered.

Affected software

CVE-2026-49834 is recorded against 2 packages.

  • github.com/sigstore/sigstore-go
  • sigstore-go (fixed in 1.2.0)

Timeline and source

Published on 9 July 2026 and last revised on 31 July 2026. No public exploit is currently recorded for this entry. A vendor advisory or fix has been published. Record sourced from NVD.

References

github.com (Web)
nvd.nist.gov (Advisory)
github.com (Web)
github.com (Web)
github.com (Package)
github.com (Web)

Details

Severity Medium
CVSS Score 5.9
CVSS Vector CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:N
CWE CWE-345
Public Exploit ✅ No
Source NVD
Published 2026-07-09
Updated 2026-08-12
Modified 2026-07-31

Affected Packages

Software From version Fixed in
github.com/sigstore/sigstore-go — —
sigstore-go — 1.2.0

Similar Threats

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