Executive brief
Suricata is a network security monitoring engine that analyzes traffic for threats. A flaw in its SMTP email parser allows attackers to craft malicious emails that evade threat detection by causing state information from outer message layers to incorrectly influence scanning of inner messages. This enables malware or suspicious files to slip past security controls.
Technical details
The SMTP MIME parser in rust/src/mime/smtp.rs fails to fully reset state when handling Content-Type: message/rfc822 encapsulated messages, causing encoding or filename attributes from an outer MIME part to leak into inner message processing. An attacker can exploit this by crafting nested MIME messages to evade file.data, file.name, or URL extraction-based detections when SMTP decoding is enabled. The fix fully resets parser state fields before processing encapsulated messages.
Affected products
- OISF Suricata 8.0.0 to 8.0.5
Timeline
- 2026-09-18: disclosed
- 2026-09-18: patched: Fixed in version 8.0.6