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OpenAdvisories
Medium · 6.0 CVE-2026-6731 EUVD-2026-39555GHSA-9c3c-227q-3j67

X.509 name constraint bypass via Subject CN treated as a DNS name

Published Jun 25, 2026 · Updated Jun 26, 2026 · Assigned by wolfSSL

Description

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.

Affected products

VendorProductAffectedFixed
wolfSSL wolfSSL 3.9.10 – ≤ 5.9.1 —

Fixed in Linux distributions

Distributions backport fixes, so the version that fixes this vulnerability differs per release — upgrade to at least the version shown. From the distributions' security trackers and advisories.

ReleasePackageFixed inAdvisory
Debian 13 wolfssl 5.7.2-0.1+deb13u2 —
Debian 12 wolfssl 5.5.4-2+deb12u3 —
ReleasePackageFixed inAdvisory
Ubuntu 26.10 wolfssl No fix yet —
Ubuntu 26.04 LTS wolfssl No fix yet —
Ubuntu 25.10 wolfssl No fix yet —
Ubuntu 24.04 LTS wolfssl No fix yet —
Ubuntu 22.04 LTS wolfssl No fix yet —
Show 3 more (older releases, extended support, other products)
ReleasePackageFixed inAdvisory
Ubuntu 20.04 LTS wolfssl No fix yet —
Ubuntu 18.04 LTS wolfssl No fix yet —
Ubuntu 16.04 LTS wolfssl No fix yet —
ReleasePackageFixed inAdvisory
Alpine v3.24 wolfssl 5.9.2-r0 —

References