CVE-2026-31931
Description
A flaw was found in Suricata, a network Intrusion Detection System (IDS), Intrusion Prevention System (IPS), and Network Security Monitoring (NSM) engine. An attacker could trigger a null dereference by using the "tls.alpn" rule keyword, causing the Suricata engine to crash. This vulnerability leads to a Denial of Service (DoS).
Statement
Important: Suricata is vulnerable to a denial of service when processing network traffic with rules that utilize the tls.alpn keyword. An attacker can trigger a null dereference, causing the Suricata engine to crash. This issue affects Suricata versions 8.0.0 through 8.0.3.
Mitigation
To mitigate this issue, avoid using the 'tls.alpn' rule keyword in Suricata configurations. If Suricata crashes due to this vulnerability, restarting the service may temporarily restore functionality. Ensure that Suricata configurations do not include the 'tls.alpn' keyword to prevent service disruption.
Understanding the Weakness (CWE)
Availability
Technical Impact: DoS: Crash, Exit, or Restart
NULL pointer dereferences usually result in the failure of the process unless exception handling (on some platforms) is available and implemented. Even when exception handling is being used, it can still be very difficult to return the software to a safe state of operation.
Integrity,Confidentiality
Technical Impact: Execute Unauthorized Code or Commands; Read Memory; Modify Memory
In rare circumstances, when NULL is equivalent to the 0x0 memory address and privileged code can access it, then writing or reading memory is possible, which may lead to code execution.
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