What is CVE-2026-39984?

CVE-2026-39984 is a medium-severity vulnerability in Sigstore Timestamp-authority, classified under Improper Certificate Validation. CVSS score: 5.5/10. Published 2026-04-14.

How severe is CVE-2026-39984?

Medium severity. CVSS v3 base score is 5.5 out of 10.

Vulnerability in Sigstore Timestamp-authority

CVE-2026-39984

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 certi…

Vulnerability class: Improper Certificate Validation

EPSS: 0.000 (0.9th percentile) — read the EPSS interpretation.

CVSS v3 metric

CVSS v3 base score 5.5 (Medium). Vector: CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:N.

Affected products

Sigstore Timestamp-authority — versions < 2.0.6

Weakness classification (CWE)

CWE-295 — Improper Certificate Validation

References

https://github.com/sigstore/timestamp-authority/security/advisories/GHSA-xm5m-wgh2-rrg3 (x_refsource_CONFIRM)
https://github.com/sigstore/timestamp-authority/releases/tag/v2.0.6 (x_refsource_MISC)

Frequently asked questions

What is CVE-2026-39984?: CVE-2026-39984 is a medium-severity vulnerability in Sigstore Timestamp-authority, classified under Improper Certificate Validation. CVSS score: 5.5/10. Published 2026-04-14.
How severe is CVE-2026-39984?: Medium severity. CVSS v3 base score is 5.5 out of 10.