Improper Certificate Validation Affecting github.com/sigstore/timestamp-authority/pkg/verification package, versions <2.0.6
Threat Intelligence
The probability is the direct output of the EPSS model, and conveys an overall sense of the threat of exploitation in the wild. The percentile measures the EPSS probability relative to all known EPSS scores. Note: This data is updated daily, relying on the latest available EPSS model version. Check out the EPSS documentation for more details.
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Test your applications- Snyk IDSNYK-GOLANG-GITHUBCOMSIGSTORETIMESTAMPAUTHORITYPKGVERIFICATION-16134929
- published23 Apr 2026
- disclosed14 Apr 2026
- creditJussi Kukkonen
Introduced: 14 Apr 2026
CVE-2026-39984 (opens in a new tab)How to fix?
Upgrade github.com/sigstore/timestamp-authority/pkg/verification to version 2.0.6 or higher.
Overview
Affected versions of this package are vulnerable to Improper Certificate Validation in the VerifyTimestampResponse function when a forged certificate is prepended to the certificate bag. An attacker can bypass authorization checks by supplying a payload where the signature is validated against one certificate, but authorization is performed against another, allowing unauthorized actions.
Note:
This is only exploitable if a user or automated system actively runs the VerifyTimestampResponse function against attacker-supplied input.
Workaround
This vulnerability can be mitigated by using the TSACertificate option to explicitly specify the exact certificate expected to be used.