alert http any any -> [$HOME_NET,$HTTP_SERVERS] any (msg:"ET WEB_SPECIFIC_APPS Alibaba fastjson2 Remote Code Execution (CVE-2026-16723)"; flow:established,to_server; http.content_type; content:"application/json"; http.request_body; strip_whitespace; content:"|22 40|type|22 3a 22|"; fast_pattern; pcre:"/^(?:jar\x3a)?[a-z]+?\x3a\x2f{2}/R"; http.method; content:"POST"; reference:url,fearsoff.org/research/fastjson-1-2-83-rce; reference:cve,2026-16723; classtype:web-application-attack; sid:2071344; rev:1; metadata:attack_target Server, tls_state TLSDecrypt, created_at 2026_07_29, cve CVE_2026_16723, deployment Perimeter, deployment Internal, deployment SSLDecrypt, confidence Medium, signature_severity Major, tag Exploit, updated_at 2026_07_29, mitre_tactic_id TA0001, mitre_tactic_name Initial_Access, mitre_technique_id T1190, mitre_technique_name Exploit_Public_Facing_Application; target:dest_ip;)