CVE-2026-89133

MEDIUMCVSS 6.3/10

Last modified

CVE-2026-89133 is a medium-severity vulnerability rated 6.3/10 on the CVSS scale. wolfSSL versions 5.9.2 and earlier contain a flaw in the X.509 certificate validation logic where it fails to properly enforce NameConstraints extensions when there is an unconstrained CA tier between a name-constrained intermediate CA and the leaf certificate. wolfSSL incorrectly accepted certificates for hostnames they shouldn't be allowed to cover, due to a chain-walking state-machine bug that resets the validation state when encountering an intermediate without NameConstraints, thereby bypassing cryptographic delegation controls.

Description

wolfSSL versions 5.9.2 and earlier contain a flaw in the X.509 certificate validation logic where it fails to properly enforce NameConstraints extensions when there is an unconstrained CA tier between a name-constrained intermediate CA and the leaf certificate. wolfSSL incorrectly accepted certificates for hostnames they shouldn't be allowed to cover, due to a chain-walking state-machine bug that resets the validation state when encountering an intermediate without NameConstraints, thereby bypassing cryptographic delegation controls. This defect exists in the default build configuration that makes use of certificates where name constraint extensions are used. Thanks to Jack Lloyd, PathDiff, and Ben Smyth for reporting the issue.

Metrics

Weakness Enumeration

Affected Software

Source: CNA advisory (CVE.org). NVD analysis pending.

VendorProductVersions
wolfSSLwolfSSL<= 5.9.2

References

Timeline

Published
Last Modified
Status
Received

Frequently Asked Questions

What is CVE-2026-89133?
wolfSSL versions 5.9.2 and earlier contain a flaw in the X.509 certificate validation logic where it fails to properly enforce NameConstraints extensions when there is an unconstrained CA tier between a name-constrained intermediate CA and the leaf certificate. wolfSSL incorrectly accepted certificates for hostnames they shouldn't be allowed to cover, due to a chain-walking state-machine bug that resets the validation state when encountering an intermediate without NameConstraints, thereby bypassing cryptographic delegation controls. This defect exists in the default build configuration that makes use of certificates where name constraint extensions are used. Thanks to Jack Lloyd, PathDiff, and Ben Smyth for reporting the issue.
How severe is CVE-2026-89133?
CVE-2026-89133 has a CVSS score of 6.3/10 (MEDIUM severity).
How do I fix CVE-2026-89133?
Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

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Source: NVD / NIST