NULL pointer dereference in QUIC server initial packet handling NULL pointer dereference in QUIC server initial packet handling (CVE-2026-42764) Severity: Moderate 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. OpenSSL 4.0, 3.6, and 3.5 are vulnerable to this issue. OpenSSL 3.4, 3.0, 1.1.1, and 1.0.2 are not affected by this issue. OpenSSL 4.0 users should upgrade to OpenSSL 4.0.1 OpenSSL 3.6 users should upgrade to OpenSSL 3.6.3 OpenSSL 3.5 users should upgrade to OpenSSL 3.5.7 This issue was reported and the fix submitted on 27th March 2026 by Sunwoo Lee (KENTECH), Hyuk Lim (KENTECH) and Seunghyun Yoon (KENTECH).
This issue has been addressed in the following products: Red Hat Enterprise Linux 10 Via RHSA-2026:25237 https://access.redhat.com/errata/RHSA-2026:25237
This issue has been addressed in the following products: Red Hat Enterprise Linux 9 Via RHSA-2026:25239 https://access.redhat.com/errata/RHSA-2026:25239