Suricata is a network Intrusion Detection System, Intrusion Prevention System and Network Security Monitoring engine. Prior to 7.0.3, specially crafted traffic can cause a heap use after free if the ruleset uses the http.request_header or http.response_header keyword. The vulnerability has been patched in 7.0.3. To work around the vulnerability, avoid the http.request_header and http.response_header keywords.
The product reuses or references memory after it has been freed. At some point afterward, the memory may be allocated again and saved in another pointer, while the original pointer references a location somewhere within the new allocation. Any operations using the original pointer are no longer valid because the memory "belongs" to the code that operates on the new pointer.