CVE-2026-22264: 
Suricata vulnerability analysis and mitigation

CVE-2026-22264 is a heap use-after-free vulnerability in Suricata, the open-source network IDS, IPS, and NSM engine, caused by an unsigned integer overflow in the alert queue expansion mechanism. It affects all Suricata versions prior to 7.0.14 (7.x branch) and versions 8.0.0 through 8.0.2 (8.x branch). The vulnerability was published on January 27, 2026, with patches released in versions 7.0.14 and 8.0.3. It carries a CVSS v3.1 base score of 9.1 (Critical) per NVD, though the GitHub Security Advisory scores it at 7.4 (High) with higher attack complexity (GitHub Advisory, Red Hat Bugzilla).

The root cause is an unsigned integer overflow (CWE-416: Use After Free) in Suricata's AlertQueueExpand() function within src/detect-engine-alert.c. The alert queue was expanded by doubling its capacity (alert_queue_capacity * 2) stored as a uint16_t without any boundary checks, meaning that when the capacity approached UINT16_MAX (65535), doubling would overflow the value back to a small number. This caused SCRealloc to allocate a smaller buffer than expected, resulting in a heap use-after-free condition when the overflowed capacity value was subsequently used to access memory beyond the reallocated buffer. The fix caps the maximum capacity at UINT16_MAX and checks for potential overflow before doubling. Exploitation requires a single packet triggering 65,536 or more matching signatures, which is only feasible with large or untrusted rulesets (GitHub Advisory, Patch Commit).

Successful exploitation can result in denial of service (crash of the Suricata process) and potential data integrity compromise, as heap use-after-free conditions can allow an attacker to corrupt memory structures. Because Suricata operates as a network security monitoring and intrusion prevention engine, crashing or corrupting it could blind the network to ongoing attacks or allow malicious traffic to pass uninspected. There is no confidentiality impact identified, but the availability and integrity impacts are rated High (GitHub Advisory, Red Hat Bugzilla).

No public proof-of-concept exploit code has been identified, and there is no evidence of in-the-wild exploitation as of the time of reporting. The EPSS score is approximately 0.044%, indicating a low probability of exploitation in the near term. The vulnerability is not listed in the CISA Known Exploited Vulnerabilities (KEV) catalog. Exploitation requires crafting network traffic that triggers an excessive number of matching signatures (≥65,536) against a single packet, which limits practical exploitability to environments running large or untrusted rulesets (GitHub Advisory, Feedly).

1. Reconnaissance: Identify network segments monitored by Suricata instances running versions prior to 7.0.14 or 8.0.3, particularly those configured with large rulesets (≥65,536 signatures).
2. Ruleset assessment: Determine whether the target Suricata deployment uses untrusted or very large rulesets where many signatures can match on the same packet — this is the key precondition for triggering the overflow.
3. Craft malicious packet: Construct a specially crafted network packet designed to match as many Suricata signatures as possible simultaneously (e.g., a packet with content patterns matching a large number of rules), aiming to trigger 65,536 or more alerts for a single packet.
4. Trigger integer overflow: Send the crafted packet through the monitored network segment. As Suricata processes the packet and attempts to expand the alert queue beyond UINT16_MAX, the uint16_t capacity value overflows, causing SCRealloc to allocate an undersized buffer.
5. Achieve heap use-after-free: The overflowed capacity value causes Suricata to write alert data beyond the bounds of the reallocated buffer, resulting in heap corruption that can crash the Suricata process (denial of service) or potentially corrupt memory in ways that affect integrity (GitHub Advisory, Patch Commit).

• Process: Unexpected crash or restart of the suricata process; core dump files generated by the Suricata process indicating a heap corruption or segmentation fault.
• Logs: Suricata log entries showing abnormally high alert counts for a single packet; memory allocation failure messages or debug logs referencing AlertQueueExpand or alert_queue_capacity overflow conditions in suricata.log.
• Network: Unusual network packets crafted to match an extremely large number of signatures simultaneously; repeated transmission of the same packet pattern from an external source.
• File System: Presence of core dump files (e.g., core.*) in the Suricata working directory following an unexpected process termination (GitHub Advisory).

Organizations should upgrade Suricata to version 7.0.14 (for the 7.x branch) or 8.0.3 (for the 8.x branch), which contain the fix that caps alert_queue_capacity at UINT16_MAX and adds overflow checks before queue expansion. If immediate patching is not possible, two workarounds are available: (1) do not run untrusted rulesets, and (2) ensure that fewer than 65,536 signatures can match on the same packet. The Suricata project released these patched versions on January 27, 2026 (GitHub Advisory, Red Hat Bugzilla).

The vulnerability was disclosed by the OISF (Open Information Security Foundation) via a GitHub Security Advisory published by Suricata maintainer victorjulien on January 27, 2026. Red Hat tracked the issue via Bugzilla and assigned it high severity/priority. Debian also issued a security notice referencing this CVE. Community discussion appeared on the Suricata forum following the release of versions 8.0.3 and 7.0.14. No significant independent researcher commentary or broad media coverage has been identified beyond standard vulnerability database aggregation (GitHub Advisory, Red Hat Bugzilla).