CVE-2025-59058: 
Rust vulnerability analysis and mitigation

CVE-2025-59058 affects httpsig-rs, a Rust implementation of IETF RFC 9421 http message signatures. The vulnerability was discovered and disclosed on September 12, 2025, impacting versions prior to 0.0.19. The issue lies in the HMAC signature comparison implementation which is not timing-safe (GitHub Advisory).

The vulnerability stems from SharedKey::sign() returning a Vec which has a non-constant-time equality implementation. The Hmac::finalize() returns a constant-time wrapper (CtOutput) which was discarded. The CVSS v3.1 base score is 5.9 (Medium) with vector string CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:N, indicating network attack vector with high complexity, requiring no privileges or user interaction (GitHub Advisory).

The vulnerability allows attackers to potentially forge signatures through timing attacks against systems using HS256 signature verification. The CVSS metrics indicate high impact on integrity while confidentiality and availability remain unaffected (GitHub Advisory).

The vulnerability has been fixed in version 0.0.19 by implementing constant-time verification using the verify_slice method instead of comparing the output bytes directly. Users should upgrade to version 0.0.19 or later to mitigate this vulnerability (GitHub Commit).