The vulnerability in wolfSSL versions 5.7.2 through 5.9.2 arises from improper client-side validation of certificates when multiple OCSP response stapling is enabled via the HAVE_CERTIFICATE_STATUS_REQUEST_V2 feature and wolfSSL_UseOCSPStaplingV2 API. The client incorrectly accepts any certificate in the peer's chain as a valid CA without verifying its authorization to act as one. This allows an attacker possessing any certificate chaining to a trusted CA, along with its private key, to forge certificates for arbitrary identities that the client will accept as valid. Additionally, the forged end entity certificate is stored persistently, impacting future connections that reuse the SSL context, even if OCSP multi usage is not enabled. This flaw was identified through internal wolfSSL testing.

An attacker who has a certificate and private key chaining to a CA trusted by the client can forge arbitrary certificates accepted as valid by the vulnerable wolfSSL client. This undermines the trust model of certificate validation, potentially allowing impersonation of arbitrary identities. The persistent storage of the forged certificate in the trust store means the impact extends beyond a single connection, affecting subsequent connections that reuse the SSL context. The CVSS v3.1 score is 6.5 (medium severity), reflecting the network attack vector, low attack complexity, required privileges, no user interaction, and impact on integrity but not confidentiality or availability.

Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. Until an official fix is available, avoid enabling OCSP stapling with the HAVE_CERTIFICATE_STATUS_REQUEST_V2 feature and wolfSSL_UseOCSPStaplingV2 with WOLFSSL_CSR2_OCSP_MULTI. Monitor wolfSSL vendor communications for patches addressing this vulnerability and apply them promptly once released.