---
id: CVE-2025-8556
aliases:
  - GHSA-2x5j-vhc8-9cwm
  - GO-2025-3754
title: 'CIRCL-Fourq: Missing and wrong validation can lead to incorrect results'
summary: 'CIRCL-Fourq: Missing and wrong validation can lead to incorrect results'
severity: low
cvss: 3.7
cvssVector: 'CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:N'
vendor: cloudflare
product: github.com/cloudflare/circl
ecosystem: go
affected:
  - github.com/cloudflare/circl < 1.6.1
patched:
  - github.com/cloudflare/circl 1.6.1
published: '2025-06-10'
updated: '2026-09-10'
sourceUpdated: '2026-09-10T03:50:24.762078780Z'
source: OSV
sourceUrl: 'https://osv.dev/vulnerability/GHSA-2x5j-vhc8-9cwm'
references:
  - url: >-
      https://github.com/cloudflare/circl/security/advisories/GHSA-2x5j-vhc8-9cwm
  - url: 'https://nvd.nist.gov/vuln/detail/CVE-2025-8556'
  - url: 'https://access.redhat.com/security/cve/CVE-2025-8556'
  - url: 'https://bugzilla.redhat.com/show_bug.cgi?id=2371624'
  - url: 'https://github.com/cloudflare/circl'
  - url: 'https://github.com/cloudflare/circl/tree/v1.6.1'
  - url: 'https://news.ycombinator.com/item?id=45669593'
  - url: >-
      https://www.botanica.software/blog/cryptographic-issues-in-cloudflares-circl-fourq-implementation
tags:
  - osv
  - go
epss: 0.00485
epssPercentile: 0.39175
ingestedAt: '2026-09-12T03:13:01.747Z'
---

## Overview

### Impact
The CIRCL implementation of FourQ fails to validate user-supplied low-order points during Diffie-Hellman key exchange, potentially allowing attackers to force the identity point and compromise session security.

Moreover, there is an incorrect point validation in ScalarMult can lead to incorrect results in the isEqual function and if a point is on the curve.


### Patches
Version 1.6.1 (https://github.com/cloudflare/circl/tree/v1.6.1) mitigates the identified issues.

We acknowledge Alon Livne (Botanica Software Labs) for the reported findings.

## Affected packages

- `github.com/cloudflare/circl < 1.6.1`

## Remediation

Upgrade to a patched release:

- `github.com/cloudflare/circl 1.6.1`