CVE-2026-55174Public exploitNetwork attack vectorHinoki check available

Invalid ECDSA signatures via missing adaptor DLEQ proof

Published Sep 30, 2026 · Updated Sep 30, 2026

ECDSA adaptor verification in UltrafastSecp256k1 before 4.2.0 lets remote attackers supply forged pre-signatures that cannot be adapted. The ecdsa_adaptor_verify and ufsecp_ecdsa_adaptor_verify functions accept an altered r value without checking a DLEQ proof that binds it to adaptor point T. Exploitation requires a malicious pre-signer and a consuming atomic-swap, DLC, or similar protocol; the resulting adapted signature fails standard ECDSA verification and can disrupt the intended settlement path.

CVSS severity5.9
Medium
EPSS probability0.15%
Next 30 days · Oct 19, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkAvailable
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Summary

What happened

ECDSA adaptor verification in UltrafastSecp256k1 before 4.2.0 lets remote attackers supply forged pre-signatures that cannot be adapted. The ecdsa_adaptor_verify and ufsecp_ecdsa_adaptor_verify functions accept an altered r value without checking a DLEQ proof that binds it to adaptor point T. Exploitation requires a malicious pre-signer and a consuming atomic-swap, DLC, or similar protocol; the resulting adapted signature fails standard ECDSA verification and can disrupt the intended settlement path.

The record

CVE
CVE-2026-55174
Published
Sep 30, 2026
Updated
Sep 30, 2026
Vendor
Vano Chkheidze
Product
UltrafastSecp256k1
Classifications
CWE-347, CWE-345
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Sep 30, 2026CVE publishedPublication date reported by the CVE source.
  2. Sep 30, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=< 4.2.0

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Vano Chkheidze · UltrafastSecp256k1version=< 4.2.0

Published CVSS scores

5.9UltrafastSecp256k1 upstream GitHub security advisoryCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Activity data is delayed. The latest report is Sep 28, 2026.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 22, 2026Sep 28, 2026
Latest reporting daySep 28, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-347Improper Verification of Cryptographic Signature
CWE-345Insufficient Verification of Data Authenticity

Public exploit references

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Technologies

Your stack

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