CVE-2026-55174: shrec UltrafastSecp256k1 · Insufficient Verification of Data Authenticity
Affects shrec UltrafastSecp256k1Source CVE Database V5
Not known to be exploited · CVSS 5.9 Medium : upgrade to 4.2.0 when convenient.
Data as of 14 Nov 2026, 20:44 UTC
- EPSS
- 0.1% chance of exploitation in 30 days – higher than 4% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
- Patch
- Available – fixed in 4.2.0
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:NExploitation evidence
Disclosed: evidence found.
CVE published 30 Sep 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors
A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 14 Nov 2026.
What to do
Upgrade UltrafastSecp256k1 and shrec/UltrafastSecp256k1 to 4.2.0.
Affected software
| Product | Affected | Fixed in |
|---|---|---|
| shrecUltrafastSecp256k1 | Affected
| Fixed in
|
GitHubshrec/UltrafastSecp256k1pkg:github/shrec/UltrafastSecp256k1Other threats | Affected
| Fixed in
|
Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.
AI-suggested
Upgrade to UltrafastSecp256k1 version 4.2.0 or later, where this vulnerability has been patched. No other mitigation is indicated by the vendor advisory.
Description
CVE-2026-55174 is a medium severity vulnerability in the shrec UltrafastSecp256k1 library prior to version 4.2.0. The issue involves insufficient verification of data authenticity in the ECDSA adaptor pre-signature verification process, where forged adaptor pre-signatures with an "r" value not cryptographically bound to the adaptor point "T" can be accepted. This flaw has been addressed in version 4.2.0.
References
- github.com/shrec/UltrafastSecp256k1/security/advisories/GHSA-c7q2-gv3g-rgxm (opens in a new tab)
- github.com/shrec/UltrafastSecp256k1/commit/5478ef566c6af91b48a45c0c61f161f5b1071981 (opens in a new tab)
- github.com/shrec/UltrafastSecp256k1/releases/tag/v4.2.0 (opens in a new tab)
- github.com/shrec/UltrafastSecp256k1/releases/tag/v4.2.1 (opens in a new tab)