A failure in the X509_verify_cert function results in wolfSSL permanently storing an unverified attacker CA within its shared CertManager. The stored CA is then trusted by all certificate consumers—including native TLS, OCSP, CRL, and direct CertManager verification—effectively allowing attackers to intercept or spoof secure communications. The vulnerability represents a cryptographic validation flaw that can lead to man‑in‑the‑middle attacks and unauthorized data exposure.

The flaw affects the wolfSSL library version 5.8.4 through 5.9.2 when compiled with the OPENSSL_EXTRA option enabled and NO_CERTS and WOLFCRYPT_ONLY disabled. Users employing these build configurations should verify whether their installations fall within that version range.

The CVSS score of 6.3 indicates a medium severity risk. EPSS data is not available, and the vulnerability is not listed in CISA’s KEV catalog. The likely attack vector is an application that calls X509_verify_cert and receives a failure during verification of a crafted or malicious certificate chain; the failure causes the malicious CA to be persisted in the library’s shared state. Once present, the CA is accepted by all consumers, enabling indiscriminate trust of attacker‑issued certificates and facilitating widespread MITM attacks. The exploit requires the application to invoke the vulnerable function, but does not need elevated privileges beyond normal operation of the affected library.