alert http any any -> $HOME_NET any (msg:"ET EXPLOIT free5GC UDR Fail-Open Abuse - Empty Body (CVE-2026-40343)"; flow:established,to_server; http.uri; content:"/nudr-dr/v2/policy-data/subs-to-notify"; fast_pattern; http.content_len; byte_test:0,=,0,0,string,dec; reference:url,dev.to/cverports/cve-2026-40343-cve-2026-40343-fail-open-request-handling-in-free5gc-udr-policy-data-subscription-5hb4; reference:cve,2026-40343; classtype:web-application-attack; sid:2068969; rev:1; metadata:attack_target Server, tls_state TLSDecrypt, created_at 2026_04_24, cve CVE_2026_40343, deployment Perimeter, deployment Internal, deployment SSLDecrypt, confidence High, signature_severity Major, tag Exploit, updated_at 2026_04_24, mitre_tactic_id TA0001, mitre_tactic_name Initial_Access, mitre_technique_id T1190, mitre_technique_name Exploit_Public_Facing_Application; target:dest_ip;)