UltrafastSecp256k1: ECDSA adaptor verification accepts non-adaptable pre-signatures due to missing DLEQ binding (CVE-2026-55174) | HOL Guard CVE

Medium · CVSS 5.9CVE-2026-55174

UltrafastSecp256k1: ECDSA adaptor verification accepts non-adaptable pre-signatures due to missing DLEQ binding

Answer in brief

CVE-2026-55174 records a Medium severity (CVSS 5.9) vulnerability in UltrafastSecp256k1: ECDSA adaptor verification accepts non-adaptable pre-signatures due to missing DLEQ binding. The current sources do not mark it as known exploited. The current feed maps shrec/UltrafastSecp256k1 (generic). Check affected ranges and fixed versions before updating.

Analysis pending evidence review

HOL Guard separates source facts from reviewed analysis. See the methodology.

Published Sep 30, 2026Updated Sep 30, 2026Source checked Sep 30, 2026First seen by HOL Sep 30, 2026Material review Sep 30, 2026

Upstream Advisory

Key facts

Risk: Medium · CVSS 5.9
Exploitation: Not marked as known exploited
Affected software: 1 mapped package or product
Fix availability: Available

Why this deserves its current priority

CVSS is 5.9. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.

Analysis status

Analysis pending evidence review

Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.

Affected scope and exposure questions

The current feed maps shrec/UltrafastSecp256k1 (generic). Check affected ranges and fixed versions before updating.

Mapped affected packages and fixed versions
Package	Affected range	Fixed version
shrec/UltrafastSecp256k1generic	<4.2.0	4.2.0

Recommended response

Check inventory. Check lockfiles and deployed manifests for shrec/UltrafastSecp256k1.
Review the reported fix. Update shrec/UltrafastSecp256k1 to 4.2.0 if you use the affected versions. Test the change in a non-production environment first.

Evidence timeline and material changes

Published upstream
Sep 30, 2026
Evidence: source:cvelist:source_dates:source-dates:record
Source modified
Sep 30, 2026
Evidence: source:cvelist:source_dates:source-dates:record
First seen by HOL
Sep 30, 2026

Sources and claim methodology

Upstream source 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.

Quoted source text, attributed separately from HOL analysis.