CVE-2025-66564
HighCVSS 7.5Exploitation Probability (EPSS)
Low risk37th percentile - higher than 37% of all known CVEs
Summary
Sigstore Timestamp Authority is a service for issuing RFC 3161 timestamps. Prior to 2.0.3, the functions api.ParseJSONRequest and api.getContentType split untrusted data (an optional OID or the Content-Type header) on period or application strings, causing O(n)-byte allocations when handling a malicious request with an excessively long OID or malformed Content-Type header. This vulnerability is fixed in 2.0.3.
Risk Assessment
An attacker could send a specially crafted request, causing excessive memory consumption and potential denial of service (DoS) in the Timestamp Authority service. This may disrupt timestamp issuance for signatures and code signing processes.
Recommendation
Upgrade Sigstore Timestamp Authority to version 2.0.3 or later.
Other vulnerabilities in Sigstore Timestamp Authority
See all- CVE-2026-49835Medium
A vulnerability in Sigstore Timestamp Authority before version 2.1.0 allows an unauthenticated remote attacker to send requests with random paths or HTTP methods, causing unbounded permanent time-series entries in Prometheus metrics and leading to memory exhaustion.
- CVE-2026-39984Medium
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.
Original NVD description (English source)
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.
Vulnerability data from NVD (NIST) · CISA KEV · EPSS