ET WEB_SPECIFIC_APPS SEPPmail Gateway RCE via Arbitrary File Write (CVE-2026-2743)

Query · suricata

flow:established,to_server;
http.uri;
content:"/v1/file.app"; fast_pattern;
http.request_body;
content:"|22|files|22 3a|";
content:"|22|file|22 3a|"; distance:0;
pcre:"/^\s*\x22[^\x22]*?(?:(?:\x2e|%+(?:25)?2[Ee]|%+(?:25)?32%+(?:25)?[46]5){1,2}(?:\x2f|\x5c|%+(?:25)?(?:25)?5[Cc]|%+(?:25)?2[Ff]){1,}){2,}/R";
http.method;
content:"POST";
target:dest_ip;
Raw source ET WEB_SPECIFIC_APPS SEPPmail Gateway RCE via Arbitrary File Write (CVE-2026-2743) · Suricata
Esc
Published by Emerging Threats Open ↗, licensed under BSD 3-Clause ↗. Line breaks added for readability; the rule is otherwise unchanged. 
alert http any any -> [$HOME_NET,$HTTP_SERVERS] any (
    msg:"ET WEB_SPECIFIC_APPS SEPPmail Gateway RCE via Arbitrary File Write (CVE-2026-2743)";
    flow:established,to_server;
    http.uri;
    content:"/v1/file.app"; fast_pattern;
    http.request_body;
    content:"|22|files|22 3a|";
    content:"|22|file|22 3a|"; distance:0;
    pcre:"/^\s*\x22[^\x22]*?(?:(?:\x2e|%+(?:25)?2[Ee]|%+(?:25)?32%+(?:25)?[46]5){1,2}(?:\x2f|\x5c|%+(?:25)?(?:25)?5[Cc]|%+(?:25)?2[Ff]){1,}){2,}/R";
    http.method;
    content:"POST";
    reference:url,labs.infoguard.ch/posts/seppmail_secure_e-mail_gateway_rce_vulnerabilities_cve-2026-2743_cve-2026-7864_cve-2026-44127_cve-2026-44128/;
    reference:cve,2026-2743;
    classtype:web-application-attack;
    sid:2069393; rev:1;
    metadata:attack_target Server, tls_state TLSDecrypt, created_at 2026_05_22, cve CVE_2026_2743, deployment Perimeter, deployment Internal, deployment SSLDecrypt, confidence High, signature_severity Major, tag Exploit, updated_at 2026_05_22, mitre_tactic_id TA0001, mitre_tactic_name Initial_Access, mitre_technique_id T1190, mitre_technique_name Exploit_Public_Facing_Application;
    target:dest_ip;
)

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