---
title: "CVE-2025-66016: cggmp21 has a missing check in the ZK proof used in CGGMP21"
url: https://erroneo.us/security/cve/CVE-2025-66016/
description: "CVE-2025-66016 (cggmp21 (crates.io (Rust))): CGGMP24 is a state-of-art ECDSA TSS protocol that supports 1-round signing (requires 3 preprocessing rounds)…"
type: vulnerability-record
section: "Security Digest"
date_published: 2025-11-25
date_modified: 2025-11-27
publisher: erroneo.us
author: erroneo.us Security Desk
cve: "CVE-2025-66016"
kev: false
cvss: 9.3
epss: 0.00186
license: All rights reserved. Quote with attribution and a link.
---

# CVE-2025-66016: cggmp21 has a missing check in the ZK proof used in CGGMP21

**Signal:** Critical and remotely reachable. No known exploitation yet, but it is network-reachable without credentials. (Computed from CISA KEV, EPSS and CVSS; not an editorial verdict.)

## Should you act?

- No confirmed exploitation. It is not in CISA’s KEV catalog and CISA’s SSVC assessment records no known exploitation. That can change quickly after a public write-up; re-check if you are affected.
- EPSS 0.2% , percentile 8: FIRST’s model estimates a 0.2% chance of exploitation activity in the next 30 days, higher than 8% of all scored CVEs (low). EPSS is a probability, not a verdict.
- Remotely reachable with no login and no user interaction. If the vulnerable service is exposed to the internet, prioritize it.
- Only applies if your dependency tree includes cggmp21 (crates.io (Rust)) < 0.6.3, fixed in 0.6.3 ; cggmp24 (crates.io (Rust)) < 0.7.0-alpha.2, fixed in 0.7.0-alpha.2 . Check your lockfile, including transitive dependencies.

## What it is

CGGMP24 is a state-of-art ECDSA TSS protocol that supports 1-round signing (requires 3 preprocessing rounds), identifiable abort, and a key refresh protocol. Prior to version 0.6.3, there is a missing check in the ZK proof that enables an attack in which single malicious signer can reconstruct full private key. This issue has been patched in version 0.6.3, for full mitigation it is recommended to upgrade to cggmp24 version 0.7.0-alpha.2 as it contains more security checks.

## Affected packages

- crates.io (Rust) `cggmp21` < 0.6.3 → fixed: 0.6.3
- crates.io (Rust) `cggmp24` < 0.7.0-alpha.2 → fixed: 0.7.0-alpha.2

## Affected products (CVE record)

- LFDT-Lockness cggmp21: < 0.6.3

## Severity

- GitHub_M CVSS 4.0: 9.3 `CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N`
- GitHub CVSS 4.0: 9.3 `CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N`

## Exploitation

- CISA KEV: not listed (no confirmed in-the-wild exploitation known to CISA).
- CISA SSVC assessment: exploitation none , automatable yes , technical impact total .
- FIRST EPSS (model of 2026-10-21): 0.19% probability of exploitation activity in the next 30 days; percentile 8.

## Sources

- [GitHub Advisory GHSA-m95p-425x-x889](https://github.com/advisories/GHSA-m95p-425x-x889)
- [CVE.org record CVE-2025-66016](https://www.cve.org/CVERecord?id=CVE-2025-66016)
- [NVD entry CVE-2025-66016](https://nvd.nist.gov/vuln/detail/CVE-2025-66016)
- [github.com](https://github.com/LFDT-Lockness/cggmp21/security/advisories/GHSA-m95p-425x-x889)
- [dfns.co](https://www.dfns.co/article/cggmp21-vulnerabilities-patched-and-explained)
- [github.com](https://github.com/LFDT-Lockness/cggmp21/commit/60e0ada5291e771d5649793329d99edd32285e72)
- [rustsec.org](https://rustsec.org/advisories/RUSTSEC-2025-0129.html)
- [rustsec.org](https://rustsec.org/advisories/RUSTSEC-2025-0130.html)

---
Source page: https://erroneo.us/security/cve/CVE-2025-66016/ · Security Digest: https://erroneo.us/security/ · More: https://erroneo.us/llms.txt