Suricata smtp/mime: incomplete state reset allows detection bypass

Suricata is a network Intrusion Detection System, Intrusion Prevention System and Network Security Monitoring engine. From 8.0.0 until 8.0.6, the SMTP MIME parser in rust/src/mime/smtp.rs does not fully reset state when processing Content-Type: message/rfc822 encapsulation. An outer MIME part's encoding or filename state can leak into the inner message, allowing crafted mail to evade detections based on file.data, file.name, or extracted URLs when SMTP MIME decoding is enabled. This issue is fixed in version 8.0.6.