Sigstore Timestamp Authority allocates excessive memory during request parsing

Vulnerability Description

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.

References

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