CVE-2025-59148 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 is classified as CWE-476, a NULL Pointer Dereference, which occurs when the software attempts to access or dereference a pointer that is NULL, leading to a segmentation fault and application crash. Specifically, versions of Suricata prior to 8.0.1 incorrectly handle the 'entropy' keyword in detection rules when it is not anchored to a "sticky" buffer. This improper handling causes Suricata to dereference a NULL pointer during rule processing, resulting in a denial of service (DoS) condition due to the segmentation fault. The vulnerability does not impact confidentiality or integrity but severely affects availability by crashing the Suricata process, potentially disabling network monitoring and protection capabilities. The issue is resolved in Suricata version 8.0.1. As a workaround, users can disable rules that use the entropy keyword or ensure that these rules are anchored to a sticky buffer to prevent the NULL pointer dereference. There are no known exploits in the wild at the time of publication, but the vulnerability is remotely exploitable without authentication or user interaction, increasing the risk profile. The CVSS v3.1 base score is 7.5 (High), reflecting the ease of exploitation and impact on availability.

For European organizations, this vulnerability poses a significant risk to network security infrastructure relying on Suricata versions below 8.0.1. Suricata is widely used in enterprise, government, and critical infrastructure sectors for real-time network traffic analysis and threat detection. Exploitation could lead to denial of service by crashing Suricata, resulting in loss of intrusion detection and prevention capabilities. This can create blind spots in network defense, increasing the risk of undetected attacks, data exfiltration, or lateral movement by threat actors. Critical sectors such as finance, energy, telecommunications, and public administration in Europe could be particularly impacted, as they often deploy Suricata for network security monitoring. The disruption could also affect compliance with regulatory requirements like GDPR and NIS Directive, which mandate robust cybersecurity measures. Although no known exploits exist yet, the vulnerability's remote and unauthenticated nature means attackers could potentially trigger crashes via crafted network traffic, making timely patching or mitigation essential to maintain operational security.

European organizations should prioritize upgrading Suricata to version 8.0.1 or later to fully remediate this vulnerability. Until patching is possible, administrators should audit their Suricata rule sets to identify any rules using the entropy keyword. Such rules should either be disabled or modified to ensure the entropy keyword is anchored to a sticky buffer, preventing the NULL pointer dereference. Network security teams should also implement monitoring to detect unexpected Suricata process crashes or restarts, which may indicate exploitation attempts. Deploying redundant Suricata instances or failover mechanisms can help maintain network visibility during potential outages. Additionally, organizations should review their incident response plans to address potential denial of service scenarios impacting network monitoring tools. Regularly updating threat intelligence feeds and collaborating with the OISF community can provide early warnings of emerging exploits targeting this vulnerability.