Certificate validation bypass via dropped name constraints
Published May 7, 2026 · Updated Aug 31, 2026
Certificate validation bypass in GnuTLS allows remote attackers to accept certificates outside a permitted namespace. The name_constraints_node_list_intersect() function returns early when the accumulated permitted list is empty, so it discards a later CA's permitted subtrees instead of adopting them. Exploitation requires a chain in which an earlier CA has only excluded constraints and a subordinate CA adds permitted constraints, enabling certificate spoofing and man-in-the-middle interception.
Summary
What happened
Certificate validation bypass in GnuTLS allows remote attackers to accept certificates outside a permitted namespace. The name_constraints_node_list_intersect() function returns early when the accumulated permitted list is empty, so it discards a later CA's permitted subtrees instead of adopting them. Exploitation requires a chain in which an earlier CA has only excluded constraints and a subordinate CA adds permitted constraints, enabling certificate spoofing and man-in-the-middle interception.
The record
- CVE
- CVE-2026-42011
- Published
- May 7, 2026
- Updated
- Aug 31, 2026
- Vendor
- 389 Directory Server
- Product
- Red Hat OpenShift Container Platform 4.16
- Classifications
- CWE-295, T1557
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- May 7, 2026CVE publishedPublication date reported by the CVE source.
- Aug 31, 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
Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.
Public exploit references
- GnuTLS empty permitted-subtrees intersection PoCproof of concept · demonstrated
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Technologies
Your stack
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Your stack
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