wolfSSL up to 5.9.2 OCSP Stapling wolfSSL_UseOCSPStaplingV2 certificate validation

Summaryinfo

A vulnerability identified as problematic has been detected in wolfSSL up to 5.9.2. The affected element is the function wolfSSL_UseOCSPStaplingV2 of the component OCSP Stapling. The manipulation leads to certificate validation. This vulnerability is uniquely identified as CVE-2026-89102. The attack is possible to be carried out remotely. No exploit exists.

Detailsinfo

A vulnerability was found in wolfSSL up to 5.9.2. It has been rated as problematic. This issue affects the function wolfSSL_UseOCSPStaplingV2 of the component OCSP Stapling. The manipulation with an unknown input leads to a certificate validation vulnerability. Using CWE to declare the problem leads to CWE-295. The product does not validate, or incorrectly validates, a certificate. Impacted is integrity. The summary by CVE is:

In wolfSSL versions 5.7.2 through 5.9.2 there is a client-side implementation flaw in RFC 6961, multiple OCSP response stapling, which can lead to certificate forgery. When a wolfSSL client enables OCSP stapling with the HAVE_CERTIFICATE_STATUS_REQUEST_V2 feature and calls wolfSSL_UseOCSPStaplingV2(ssl, WOLFSSL_CSR2_OCSP_MULTI, options), the client accepts any certificate in the peer's chain as a certificate authority without verifying that the certificate is actually authorized to act as one. This means that an attacker who possesses any certificate that chains to a CA trusted by the client (along with its private key) can forge certificates for arbitrary identities that will be accepted as valid by the client. The end entity certificate of the server is stored in the persistent trust store, affecting subsequent connections that reuse the context even when OCSP multi usage is not employed. Found by internal wolfSSL testing.

It is possible to read the advisory at github.com. The identification of this vulnerability is CVE-2026-89102 since 09/11/2026. The exploitation is known to be difficult. The attack may be initiated remotely. No form of authentication is needed for a successful exploitation. Technical details of the vulnerability are known, but there is no available exploit. The pricing for an exploit might be around USD $0-$5k at the moment (estimation calculated on 09/27/2026). The attack technique deployed by this issue is T1587.003 according to MITRE ATT&CK.

There is no information about possible countermeasures known. It may be suggested to replace the affected object with an alternative product.

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Productinfo

Name

• wolfSSL

Version

• 5.9.0
• 5.9.1
• 5.9.2

License

• open-source

Website

• Product: https://github.com/wolfSSL/wolfssl/

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