X.509 Certificate Validation Flaw in wolfSSL Affects Security
CVE-2026-89133

6.3MEDIUM

Key Information:

Vendor

Wolfssl

Status
Wolfssl
Vendor
CVE Published:
27 September 2026

What is CVE-2026-89133?

wolfSSL versions 5.9.2 and earlier have a vulnerability in their X.509 certificate validation system, particularly in how NameConstraints extensions are enforced. The flaw allows certificates to be incorrectly accepted for hostnames that should be restricted due to an issue with the chain-walking state machine. This bug occurs when an intermediate Certificate Authority (CA) does not have NameConstraints applied, inadvertently bypassing the established cryptographic delegation controls. This issue primarily surfaces in the default build configuration that relies on certificates utilizing name constraint extensions. The vulnerability highlights the importance of strict validation checks in cryptographic standards to prevent unauthorized access.

Affected Version(s)

wolfSSL 0 <= 5.9.2

References

https://github.com/wolfSSL/wolfssl/pull/10687

CVSS V4

Score:
6.3
Severity:
MEDIUM
Confidentiality:
Low
Integrity:
Low
Availability:
None
Attack Vector:
Network
Attack Complexity:
High
Attack Required:
None
Privileges Required:
Undefined
User Interaction:
None

Timeline

  • Vulnerability published

  • Vulnerability Reserved

Credit

Jack Lloyd
PathDiff
Ben Smyth
.