Raw vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:HSummary
CVE-2025-66564 is a high-severity Amplification (CWE-405) vulnerability in Linuxfoundation Sigstore Timestamp Authority. Its CVSS base score is 7.5 (High).
Operationally, exploitation aligns with the MITRE ATT&CK technique Application or System Exploitation (T1499.004); ranked at the 35th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog.
The strongest mitigations our analysis identified map to SI-10 (Information Input Validation) and SC-5 (Denial-of-service Protection) — see the control section below for these in your framework.
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2025-201319
Vulnerability Data
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…
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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.
- CWE(s)
Related Threats
MITRE ATT&CK Enterprise TechniquesAI
Why these techniques?
CWE-405 resource exhaustion via malicious untrusted input to public API directly enables application-layer DoS through exploitation of the parsing flaw.
CVEs Like This One
Affected Assets
Mitigating Controls
Control response
Mitigating Controls (NIST 800-53 r5) AI
Directly requires validation of untrusted inputs (OID strings and Content-Type headers) before parsing/splitting to block the O(n) allocation amplification.
Provides denial-of-service protection controls that can limit resource exhaustion from malicious requests exploiting the split operations.
Enables monitoring and analysis of API request patterns to identify anomalous inputs that trigger excessive allocations in ParseJSONRequest or getContentType.
Mitigating Controls (NIST CSF 2.0) AI
Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→CSF cross-walk (authority under review) — links open the control.
Resilience mechanisms such as rate limiting and load balancing directly constrain asymmetric resource use.
Capacity planning and monitoring maintain availability headroom against amplification attacks.
Network monitoring detects amplification traffic patterns but does not itself limit asymmetric consumption.
Runtime resource monitoring can surface excessive consumption yet does not enforce authorization or work proofs.
Mitigating Controls (ISO/IEC 27001:2022 Annex A) AI
Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→ISO cross-walk (authority under review) — links open the control.
Stress-testing and demand-reduction tactics (e.g., bandwidth throttling) blunt amplification vectors that would otherwise let an attacker multiply resource consumption through a single request.