SB2025111412 - Session security compromise in Cloudflare circl
Published: November 14, 2025
Security Bulletin ID
SB2025111412
CSH Severity
Medium
Patch available
YES
Number of vulnerabilities
1
Exploitation vector
Remote access
Highest impact
Information disclosure
Breakdown by Severity
- Low
- Medium
- High
- Critical
Description
This security bulletin contains information about 1 vulnerability.
1) Cryptographic issues (CVE-ID: CVE-2025-8556)
CWE-ID: CWE-310 - Cryptographic Issues
CVSSv4: CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N/E:U/U:Green
The vulnerability allows a remote attacker to compromise session security.
The vulnerability exists due to an error in FourQ elliptic curve implementation and incorrect point validation during Diffie-Hellman key exchange. A remote attacker can compromise session security via low-order point injection and gain access to sensitive information.
Remediation
Install update from vendor's website.
References
- https://access.redhat.com/security/cve/CVE-2025-8556
- https://bugzilla.redhat.com/show_bug.cgi?id=2371624
- https://github.com/cloudflare/circl/security/advisories/GHSA-2x5j-vhc8-9cwm
- https://github.com/cloudflare/circl/tree/v1.6.1
- https://news.ycombinator.com/item?id=45669593
- https://www.botanica.software/blog/cryptographic-issues-in-cloudflares-circl-fourq-implementation