CVE-2026-42764: NULL Pointer Dereference in QUIC Server Initial Packet Handling
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 SSLLISTENERFLAGNOVALIDATE is used with the SSLnewlistener() 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 Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
- Upgrade
Upgrade to a fixed release to a version that resolves this vulnerability.
Fixed in 3.5.7 - Upgrade
Upgrade to a fixed release to a version that resolves this vulnerability.
Fixed in 3.6.3 - Upgrade
Upgrade to a fixed release to a version that resolves this vulnerability.
Fixed in 4.0.1
Event History
Frequently Asked Questions
What is the severity of CVE-2026-42764?
The severity of CVE-2026-42764 is high with a CVSS score of 7.5.
How does CVE-2026-42764 affect OpenSSL?
CVE-2026-42764 affects OpenSSL by allowing a NULL pointer dereference in the QUIC server when receiving an invalid token.
What are the potential impacts of CVE-2026-42764?
The potential impact of CVE-2026-42764 includes abnormal termination of the QUIC server process leading to Denial of Service.
How can I mitigate CVE-2026-42764?
To mitigate CVE-2026-42764, ensure address validation is enabled in the OpenSSL configuration.
In which versions of OpenSSL is CVE-2026-42764 present?
CVE-2026-42764 is present in versions of OpenSSL that handle QUIC server initial packets without proper token validation.