CVE-2025-59150 is a high-severity vulnerability affecting Suricata, an open-source network intrusion detection system (IDS), intrusion prevention system (IPS), and network security monitoring (NSM) engine developed by the Open Information Security Foundation (OISF). The vulnerability exists in Suricata version 8.0.0 and is related to the handling of the tls.subjectaltname keyword, which is used in Suricata rules to inspect the Subject Alternative Name (SAN) field in TLS certificates. Specifically, when Suricata decodes a subjectAltName field containing a NULL byte, it triggers a NULL pointer dereference (CWE-476), causing a segmentation fault that crashes the Suricata process. This results in a denial of service (DoS) condition, as the IDS/IPS engine becomes unavailable until restarted or remediated. The issue is fixed in Suricata version 8.0.1. Until upgrading, a workaround is to disable any detection rules that use the tls.subjectaltname keyword to avoid triggering the crash. The vulnerability has a CVSS v3.1 base score of 7.5, indicating high severity, with an attack vector of network (AV:N), low attack complexity (AC:L), no privileges required (PR:N), no user interaction needed (UI:N), and impacts availability only (A:H) without affecting confidentiality or integrity. No known exploits are reported in the wild as of the published date. This vulnerability highlights the risks of malformed TLS certificate fields causing instability in security monitoring tools, which can be exploited by attackers to disrupt network defense mechanisms.

For European organizations, the impact of this vulnerability can be significant, especially for those relying on Suricata for network security monitoring and intrusion prevention. A successful exploitation leads to a denial of service by crashing the Suricata process, potentially leaving networks blind to malicious traffic and attacks during the downtime. This gap in detection can be exploited by attackers to conduct further intrusions, data exfiltration, or lateral movement without being detected. Critical infrastructure operators, financial institutions, and enterprises with high compliance requirements (e.g., GDPR) may face increased risk of security incidents and regulatory consequences if their IDS/IPS systems are disrupted. Additionally, the downtime may affect incident response capabilities and delay threat detection. Given Suricata’s usage in various sectors across Europe, the vulnerability could impact a broad range of organizations, especially those with automated security operations relying on continuous monitoring. The lack of required privileges or user interaction for exploitation increases the risk, as attackers can trigger the fault remotely by sending specially crafted TLS traffic containing NULL bytes in the subjectAltName field.

To mitigate this vulnerability, European organizations should prioritize upgrading Suricata to version 8.0.1 or later, where the issue is fixed. If immediate upgrading is not feasible, organizations should disable all Suricata rules that use the tls.subjectaltname keyword to prevent triggering the NULL pointer dereference. Network administrators should also monitor Suricata logs for unexpected crashes or restarts that may indicate attempted exploitation. Implementing network-level filtering to block suspicious TLS traffic with malformed certificates may reduce exposure. Additionally, organizations should ensure that Suricata runs with appropriate process supervision and automatic restart mechanisms to minimize downtime. Regularly updating Suricata and its rule sets, combined with comprehensive network monitoring, will help detect and respond to attempts to exploit this vulnerability. Finally, organizations should review their incident response plans to address potential IDS/IPS outages and maintain alternative detection capabilities during Suricata downtime.