OpenSSL NULL Pointer Dereference Vulnerability - CVE-2026-42764

Issue summary: Receiving a QUIC initial packet with an invalid token may trigger a NULL pointer dereference in the OpenSSL QUIC server with address validation disabled. Impact summary: NULL pointer dereference typically causes abnormal termination of the affected QUIC server process and a Denial of Service. If the address validation is disabled in the OpenSSL QUIC server implementation an attacker can crash the server by sending an initial packet with an invalid or expired token. By default the client address validation is enabled in the OpenSSL QUIC server implementation which makes the default configuration not vulnerable to this issue. However if the SSL_LISTENER_FLAG_NO_VALIDATE is used with the SSL_new_listener() call the address validation is disabled making the vulnerable code reachable. The FIPS modules in 4.0 3.6 3.5 3.4 and 3.0 are not affected by this issue as the affected code is outside the OpenSSL FIPS module boundary.