Session-key compromise via low-order point acceptance
Published Aug 6, 2025 · Updated Feb 25, 2026
Improper point validation in Cloudflare CIRCL before 1.6.1 allows remote attackers to compromise FourQ Diffie-Hellman session keys. Point.Unmarshal omits a second curve check after conjugation, while Curve4Q Shared accepts low-order or identity results and pointR1 treats invalid Z=0 coordinates incorrectly. An attacker must supply a chosen public point to an application using the vulnerable shared-secret path; the bounded consequence is disclosure of affected session secrets.
Summary
What happened
Improper point validation in Cloudflare CIRCL before 1.6.1 allows remote attackers to compromise FourQ Diffie-Hellman session keys. Point.Unmarshal omits a second curve check after conjugation, while Curve4Q Shared accepts low-order or identity results and pointR1 treats invalid Z=0 coordinates incorrectly. An attacker must supply a chosen public point to an application using the vulnerable shared-secret path; the bounded consequence is disclosure of affected session secrets.
The record
- CVE
- CVE-2025-8556
- Published
- Aug 6, 2025
- Updated
- Feb 25, 2026
- Vendor
- 389 Directory Server
- Product
- Red Hat OpenShift Serverless
- Classifications
- CWE-1287, CWE-20
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Aug 6, 2025CVE publishedPublication date reported by the CVE source.
- Feb 25, 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?
Affected versions are unavailable in this record. Check the vendor advisory for version and patch details.
What conditions does exploitation require?
What is affected?
Published CVSS scores
CVSS describes severity. EPSS estimates exploitation probability.
Attacks
What attackers are doing with it
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Weakness, pattern, technique
Public exploit references
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Technologies
Your stack
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Your stack
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