UltrafastSecp256k1: ECDSA adaptor verification accepts non-adaptable pre-signatures due to missing DLEQ binding
Priority MEDIUM 60CWE-345Published · Updated
Key facts
- Attack vector
- Network
- Privileges required
- None
- User interaction
- None
- Attack complexity
- High
- Impact type
- Security bypass
- Confidentiality · integrity · availability
- None · High · None
- Fix status
- Fixed
Attack profile from CVSS 3.1 · CNA. Fix status from CNA. Impact type from CWE-345.
Summary
UltrafastSecp256k1 is a high-performance, multi-backend secp256k1 engine with reproducible audit evidence, compatibility shims, and profile-based review scopes. Prior to version 4.2.0, UltrafastSecp256k1's ECDSA adaptor pre-signature verification accepts forged adaptor pre-signatures whose "r" value is not cryptographically bound to the adaptor point "T". This issue has been patched in version 4.2.0.
Why it matters now
Exploitation Proof of concept CISA SSVC · not in CISA KEV
EPSS 0.0015 4th percentileScored 2026-11-07
Fix Fixed UltrafastSecp256k1 (shrec): 4.2.0
SSVC decision points
CISA ADP · SSVC 2.0.3
- Exploitation
- Poc
- Automatable
- No
- Technical impact
- Partial
The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.
Affected products
Remediation
- Fix · CNA UltrafastSecp256k1 (shrec) Fixed in 4.2.0
Timeline
- 2026-10-02 Threatist record created from CVE-2026-55174
References
Other 4
- https://github.com/shrec/UltrafastSecp256k1/security/advisories/GHSA-c7q2-gv3g-rgxm
- https://github.com/shrec/UltrafastSecp256k1/commit/5478ef566c6af91b48a45c0c61f161f5b1071981
- https://github.com/shrec/UltrafastSecp256k1/releases/tag/v4.2.0
- https://github.com/shrec/UltrafastSecp256k1/releases/tag/v4.2.1
Sources
This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences