# CVE-2026-39984: golang-github-sigstore-timestamp-authority: Sigstore Timestamp Authority is a service for issuing RFC 3161 timestamps

CVE-2026-39984 is fixed in 4 products on 1 platform, first by DEBIAN-CVE-2026-39984, released April 15, 2026. It is not reported as exploited. Patch Radar priority: Routine.

- Web page: https://patchblox.com/security/cve/CVE-2026-39984
- Priority: Routine
- CVSS: 5.5 (medium)
- EPSS: 0.0010
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: Apr 15, 2026

## Description

Sigstore Timestamp Authority is a service for issuing RFC 3161 timestamps. Versions 2.0.5 and below contain an authorization bypass vulnerability in the VerifyTimestampResponse function. VerifyTimestampResponse correctly verifies the certificate chain signature, but the TSA-specific constraint checks in VerifyLeafCert uses the first non-CA certificate from the PKCS#7 certificate bag instead of the leaf certificate from the verified chain. An attacker can exploit this by prepending a forged certificate to the certificate bag while the message is signed with an authorized key, causing the library to validate the signature against one certificate but perform authorization checks against another. This vulnerability only affects users of the timestamp-authority/v2/pkg/verification package and does not affect the timestamp-authority service itself or sigstore-go. The issue has been fixed in version 2.0.6.

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Linux | docker opensuse-leap 16.0 | 29.7.2_ce-160000.8.1 | [OPENSUSE-SU-2026:22158-1](https://patchblox.com/security/data/fix/linux/opensuse-su-2026-22158-1.md) | Nov 7, 2026 |
| Linux | docker sles 15.6 | 29.4.0_ce-150000.253.1 | [SUSE-SU-2026:2692-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-2692-1.md) | Jun 30, 2026 |
| Linux | docker sles 15.7 | 29.4.0_ce-150000.253.1 | [SUSE-SU-2026:2692-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-2692-1.md) | Jun 30, 2026 |
| Linux | docker sles 16.0 | 29.4.0_ce-160000.7.1 | [SUSE-SU-2026:22367-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-22367-1.md) | Jun 25, 2026 |
| Linux | golang-github-sigstore-timestamp-authority Debian 14 | 2.1.0-1 | [DEBIAN-CVE-2026-39984](https://patchblox.com/security/data/fix/linux/debian-cve-2026-39984.md) | Apr 15, 2026 |
| Linux | govulncheck-vulndb opensuse-leap 16.0 | 0.0.20260723T184607-160000.1.1 | [OPENSUSE-SU-2026:21483-1](https://patchblox.com/security/data/fix/linux/opensuse-su-2026-21483-1.md) | Jul 30, 2026 |
| Linux | nerdctl amzn 2023 | 2.2.2-1.amzn2023.0.1 | [ALAS2023-2026-1605](https://patchblox.com/security/data/fix/linux/alas2023-2026-1605.md) | Apr 27, 2026 |

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Data as of 2026-11-09T01:18:40Z UTC. Source: Patchblox Patch Radar (https://patchblox.com/security/patch-radar). Patchblox finds out-of-date software on Windows, macOS and Linux and updates it through release rings: https://patchblox.com/demo

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