alert http any any -> [$HOME_NET,$HTTP_SERVERS] any (msg:"ET WEB_SPECIFIC_APPS Atlassian MCP Server-side Request Forgery via HTTP Headers (CVE-2026-27826) M1"; flow:established,to_server; http.uri; content:"/mcp"; http.header; content:"x-atlassian-jira-url|3a 20|http"; fast_pattern; nocase; content:"x-atlassian-jira-personal-token|3a 20|"; http.method; content:"POST"; reference:url,pluto.security/blog/mcpwnfluence-cve-2026-27825-critical/; reference:cve,2026-27826; classtype:web-application-attack; sid:2071904; rev:1; metadata:affected_product Atlassian, attack_target Server, tls_state TLSDecrypt, created_at 2026_09_02, cve CVE_2026_27826, deployment Perimeter, deployment Internal, confidence High, signature_severity Major, tag Exploit, updated_at 2026_09_02, mitre_tactic_id TA0001, mitre_tactic_name Initial_Access, mitre_technique_id T1190, mitre_technique_name Exploit_Public_Facing_Application; target:dest_ip;)