alert http $EXTERNAL_NET any -> $HTTP_SERVERS $HTTP_PORTS (msg:"VEDAS CVE-2026-20131 Cisco Secure Firewall Management Center - Java Deserialization RCE Attempt"; flow:established,to_server; http.method; content:"POST"; http.header; content:"application/x-java-serialized-object"; nocase; fast_pattern; http.request_body; content:"|ac ed 00 05|"; startswith; classtype:web-application-attack; reference:cve,CVE-2026-20131; reference:url,https://www.exploit.observer/?keyword=CVE-2026-20131&match=exact; reference:url,https://subdomain.center/?engine=ammonites&keyword=cisco&match=exact; sid:1087600; rev:1;)