---
id: CVE-2026-89133
title: >-
  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 a…
summary: >-
  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 a…
severity: medium
cvss: 6.3
cvssVector: 'CVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N'
cwe:
  - CWE-295
vendor: wolfSSL
product: wolfSSL
affected:
  - wolfSSL <= 5.9.2
published: '2026-09-27'
updated: '2026-09-27'
sourceUpdated: '2026-09-27T10:16:58.900'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-89133'
references:
  - url: 'https://github.com/wolfSSL/wolfssl/pull/10687'
    label: facts@wolfssl.com
tags:
  - nvd
  - cve.org
cvssSource: cna
ingestedAt: '2026-09-27T09:45:46.030Z'
---

## Overview

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.

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.