wolfSSL DNS CN name constraint bypass (CVE-2026-6731)
CVE-2026-6731 Published on June 25, 2026
X.509 name constraint bypass via Subject CN treated as a DNS name
X.509 name constraint bypass via the Subject Common Name when treated as a DNS-type name. A certificate whose Subject CN violates an issuing CA's DNS name constraints could be accepted.
Weakness Type
Improper Certificate Validation
The software does not validate, or incorrectly validates, a certificate. When a certificate is invalid or malicious, it might allow an attacker to spoof a trusted entity by interfering in the communication path between the host and client. The software might connect to a malicious host while believing it is a trusted host, or the software might be deceived into accepting spoofed data that appears to originate from a trusted host.
Products Associated with CVE-2026-6731
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Affected Versions
wolfSSL:- Version 3.9.10, <= 5.9.1 is affected.