CVE-2026-55174 UltrafastSecp256k1: ECDSA adaptor verification accepts non-adaptable pre-signatures due to missing DLEQ binding
Attackers can forge ECDSA adaptor pre-signatures due to missing cryptographic binding, bypassing verification in the UltrafastSecp256k1 library.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2026-55174?
CVE-2026-55174 is a medium-severity vulnerability in shrec UltrafastSecp256k1, published on 30 Sep 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
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.
Which versions are affected by CVE-2026-55174?
How do I fix CVE-2026-55174?
No fix has been published for CVE-2026-55174 yet. Limit exposure of the affected software until one is available.
Is CVE-2026-55174 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-55174 exists.
Sources
Also known as GHSA-c7q2-gv3g-rgxm.