What is CVE-2025-66564?

CVE-2025-66564 is a high-severity vulnerability in Sigstore Timestamp-authority, classified under Asymmetric Resource Consumption (Amplification). CVSS score: 7.5/10. Published 2025-12-04.

How severe is CVE-2025-66564?

High severity. CVSS v3 base score is 7.5 out of 10.

Vulnerability in Sigstore Timestamp-authority

CVE-2025-66564

Sigstore Timestamp Authority is a service for issuing RFC 3161 timestamps. Prior to 2.0.3, Function api.ParseJSONRequest currently splits (via a call to strings.Split) an optionally-provided OID (which is untrusted data) on periods. Simila…

EPSS: 0.000 (5.4th percentile) — read the EPSS interpretation.

CVSS v3 metric

CVSS v3 base score 7.5 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H.

Affected products

Sigstore Timestamp-authority — versions < 2.0.3

Weakness classification (CWE)

CWE-405 — Asymmetric Resource Consumption (Amplification)

References

https://github.com/sigstore/timestamp-authority/security/advisories/GHSA-4qg8-fj49-pxjh (x_refsource_CONFIRM)
https://github.com/sigstore/timestamp-authority/commit/0cae34e197d685a14904e0bad135b89d13b69421 (x_refsource_MISC)

Frequently asked questions

What is CVE-2025-66564?: CVE-2025-66564 is a high-severity vulnerability in Sigstore Timestamp-authority, classified under Asymmetric Resource Consumption (Amplification). CVSS score: 7.5/10. Published 2025-12-04.
How severe is CVE-2025-66564?: High severity. CVSS v3 base score is 7.5 out of 10.