CVE-2025-66564: Linuxfoundation Sigstore Timestamp Authority

High severity, CVSS 7.5. EPSS: 0.4% chance of exploitation in the next 30 days.

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. Similarly, function api.getContentType splits the Content-Type header (which is also untrusted data) on an application string. As a result, in the face of a malicious request with either an excessively long OID in the payload containing many period characters or a malformed Content-Type header, a call to api.ParseJSONRequest or api.getContentType incurs allocations of O(n) bytes (where n stands for the length of the function's argument). This vulnerability is fixed in 2.0.3.

Affected products

• Linuxfoundation Sigstore Timestamp Authority: before 2.0.3 (fixed in 2.0.3)

Published 2025-12-04. Last modified 2026-06-17.