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OCSP stapling v2 multi accepts non-CA chain certificates as issuers

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.

Announced 27 Sept 2026