In Suricata before 4.x, it was possible to trigger lots of redundant checks on the content of crafted network traffic with a certain signature, because of DetectEngineContentInspection in detect-engine-content-inspection.c. The search engine doesn't stop when it should after no match is found; instead, it stops only upon reaching inspection-recursion-limit (3000 by default).

Suricata before 3.2.1 has an IPv4 defragmentation evasion issue caused by lack of a check for the IP protocol during fragment matching.