# CVE-2026-89134: wolfSSL certificate name-constraint bypass via SAN mismatch

Source: https://junglewise.ai/threats/cve-2026-89134-a-certificate-with-no-dnsname-san-but-another-san-type-present-e  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-09-27. Updated: 2026-09-27  
License: CC BY 4.0 with a link back

CVE-2026-89134 · Severity: info · Published 2026-09-27

wolfSSL, a TLS/SSL library used in embedded systems and IoT devices, has a flaw in how it validates certificate names against policy constraints. An attacker can present a certificate with alternative names (like IP addresses) instead of domain names, allowing it to bypass security policies that should restrict which names a certificate can be used for. This could allow forged certificates to be accepted in contexts where they should be rejected.

Technologies: [Wolfssl](https://junglewise.ai/threats/technologies/wolfssl). Vendors: [Wolfssl](https://junglewise.ai/threats/vendors/wolfssl).

## Quick answers

**Is CVE-2026-89134 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-89134 being exploited in the wild.

**How severe is CVE-2026-89134?** Informational severity, published 27 September 2026.

**Which products and versions are affected?** Wolfssl 5.9.2 and later (prior to fix).

**Is there a fix for CVE-2026-89134?** A patch was published on 2026-07-08. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-89134 attacked?** It is attacked over the network, in a software library.

**Am I affected by CVE-2026-89134?** Check whether you run Wolfssl at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## Technical details

The vulnerability exists in the name-constraint validation logic in wolfSSL's certificate chain verification. A certificate lacking a dNSName Subject Alternative Name (SAN) but containing other SAN types (e.g., registeredID or iPAddress) bypasses the CN-as-DNS fallback check due to incomplete logic that only verifies the altNames field is NULL rather than checking for the absence of dNSName SANs. This is a regression from an incomplete fix to CVE-2026-6731 introduced in version 5.9.2, allowing out-of-scope CNs to be accepted when policy constraints should apply.

## Affected products

- wolfSSL wolfSSL 5.9.2 and later (prior to fix)

## Timeline

- 2026-09-27: disclosed
- 2026-07-08: patched

## References

- [https://github.com/wolfSSL/wolfssl/pull/10837](https://github.com/wolfSSL/wolfssl/pull/10837)

## Related threats

- [wolfSSL certificate validation bypass in ConfirmNameConstraints()](https://junglewise.ai/threats/cve-2026-95208-an-issue-in-the-confirmnameconstraints-function-wolfcrypt-src-asn)
- [wolfSSL revocation check bypass with OCSP and CRL](https://junglewise.ai/threats/cve-2026-94417-when-an-application-enables-both-ocsp-and-crl-revocation-checking)
- [wolfSSL TLS 1.2 ChangeCipherSpec message ordering bypass](https://junglewise.ai/threats/cve-2026-93304-a-d-tls-1-2-client-can-accept-a-changecipherspec-message-before)
- [wolfSSL MatchTrustedPeer public key validation bypass](https://junglewise.ai/threats/cve-2026-93302-matchtrustedpeer-ignores-the-public-key-used-leading-to-forged-ca)
- [wolfSSL TLS authentication bypass in Raw Public Key handling](https://junglewise.ai/threats/cve-2026-89136-when-using-rpk-raw-public-key-the-client-side-of-a-tls-1-2-1-3)