CVE-2026-31932: 
Suricata vulnerability analysis and mitigation

CVE-2026-31932 is a denial-of-service vulnerability in Suricata, the open-source network IDS, IPS, and NSM engine, caused by inefficient KRB5 (Kerberos 5) buffering with quadratic algorithmic complexity. It affects all Suricata versions prior to 7.0.15 and versions 8.0.0 through 8.0.3. The vulnerability was published on April 2, 2026, with the security advisory authored by the OISF team on March 31, 2026. It carries a CVSS v3.1 base score of 7.5 (High) (GitHub Advisory, Red Hat Bugzilla).

The root cause is classified under CWE-407 (Inefficient Algorithmic Complexity) and CWE-770 (Allocation of Resources Without Limits or Throttling). Suricata's KRB5 protocol parser exhibits quadratic complexity when buffering Kerberos 5 traffic, meaning that specially crafted network packets can trigger worst-case computational behavior and cause unbounded resource consumption. An unauthenticated remote attacker can exploit this by sending crafted KRB5 traffic over the network — no privileges or user interaction are required. A workaround of disabling the krb5 parser is noted in the official advisory (GitHub Advisory).

Successful exploitation causes significant performance degradation of the Suricata engine, effectively resulting in a Denial of Service (DoS) that can blind or disable network intrusion detection and prevention capabilities. There is no impact on confidentiality or data integrity — the sole impact is on availability (CVSS Availability: High). Because Suricata functions as a network security monitor, its degradation or failure could allow malicious traffic to pass undetected, indirectly increasing organizational risk (GitHub Advisory, Red Hat Bugzilla).

There is no public proof-of-concept exploit and no evidence of in-the-wild exploitation at this time (Feedly). The vulnerability is not listed in the CISA Known Exploited Vulnerabilities (KEV) catalog. The EPSS score is approximately 0.04%, reflecting a low probability of near-term exploitation. However, the attack requires no authentication, no user interaction, and is remotely exploitable over the network, making it straightforward to attempt if targeted.

1. Reconnaissance: Identify network segments or hosts running Suricata versions prior to 7.0.15 or 8.0.0–8.0.3 that monitor Kerberos traffic (typically on port 88/TCP or 88/UDP).
2. Craft malicious KRB5 traffic: Construct specially crafted Kerberos 5 protocol messages designed to trigger worst-case quadratic buffering behavior in Suricata's KRB5 parser.
3. Transmit traffic to monitored network: Send the crafted KRB5 packets across a network segment monitored by the target Suricata instance, so the engine processes the traffic.
4. Trigger resource exhaustion: The inefficient buffering algorithm causes Suricata to consume excessive CPU and/or memory resources, leading to performance degradation or a complete DoS of the monitoring engine.
5. Achieve objective: With Suricata degraded or unresponsive, the attacker's subsequent malicious network activity may go undetected (GitHub Advisory).

• Process: Suricata process exhibiting abnormally high CPU or memory utilization, particularly when processing Kerberos traffic on port 88.
• Logs: Suricata logs showing repeated or sustained KRB5 parser activity, performance warnings, or engine slowdown messages around the time of suspicious Kerberos traffic spikes.
• Network: Unusual volume of Kerberos 5 (port 88/TCP or UDP) traffic from unexpected or external sources directed at monitored network segments.
• System: Suricata alert drops or gaps in detection logs indicating the engine was overwhelmed or unresponsive during a specific time window.

Upgrade Suricata to version 7.0.15 (for the 7.x branch) or 8.0.4 (for the 8.x branch), which contain the fix for this vulnerability (GitHub Advisory). As an immediate workaround for organizations unable to patch promptly, disable the krb5 parser in the Suricata configuration. Additionally, consider implementing network segmentation to limit exposure of Suricata monitoring interfaces to untrusted traffic sources until patching is complete (Feedly).

The Suricata project released versions 7.0.15 and 8.0.4 on March 17, 2026, addressing this and other issues, with the CVE formally published on April 2, 2026 (Suricata Release). Red Hat tracked the issue via Bugzilla and classified it as high severity (Red Hat Bugzilla). openSUSE issued a security announcement for affected packages, and the vulnerability received coverage from security community outlets including Mastodon security accounts and infosec blogs (openSUSE, Infinit Sec).