CVE-2026-42764: NULL Pointer Dereference in QUIC Server Initial Packet Handling

Severity: high (CVSS 7.5 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 1.2% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-06-09 · updated 2026-07-23
Weakness: CWE-476

Description

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.

Affected products

OpenSSL: from 3.5.0 before 3.5.7; from 3.6.0 before 3.6.3; 4.0.0 — fixed in 3.5.7, 3.6.3

How to fix

Upgrade to a fixed version: OpenSSL 3.5.7, 3.6.3. Check the vendor advisory for mitigations.

References

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