CVE-2024-25584 in OX Dovecot Pro
Summary
by MITRE • 09/06/2024
Dovecot accepts dot LF DOT LF symbol as end of DATA command. RFC requires that it should always be CR LF DOT CR LF. This causes Dovecot to convert single mail with LF DOT LF in middle, into two emails when relaying to SMTP. Dovecot will split mail with LF DOT LF into two mails. Upgrade to latest released version. No publicly available exploits are known.
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Analysis
by VulDB Data Team • 09/06/2024
The vulnerability identified as CVE-2024-25584 affects Dovecot email servers and represents a protocol implementation flaw that stems from improper handling of line ending sequences during email data transmission. This issue specifically impacts the SMTP DATA command processing where Dovecot incorrectly interprets the sequence LF DOT LF as a valid end-of-data marker, deviating from the standard RFC specification that mandates CR LF DOT CR LF sequences for proper termination. The deviation from established protocols creates a condition where email content containing legitimate line feed followed by dot and line feed sequences gets misinterpreted by the server.
The technical flaw manifests when Dovecot encounters email messages containing the LF DOT LF pattern within the message body, particularly in contexts where such sequences might appear naturally in email content or when processing messages from various email clients or servers. When this occurs, the server's incorrect interpretation causes it to split a single email message into two separate messages during the relaying process to downstream SMTP servers. This behavior fundamentally alters the email delivery process and can result in message fragmentation that disrupts normal email communication workflows.
The operational impact of this vulnerability extends beyond simple message splitting to potentially cause significant disruption in email services and communication integrity. When emails are incorrectly split, recipients may receive incomplete messages, and email systems may experience unexpected behavior in their processing pipelines. The vulnerability affects email relay operations where Dovecot serves as an intermediary between email servers, potentially causing downstream systems to process malformed or fragmented messages. This issue particularly impacts environments where email content might legitimately contain line feed followed by dot sequences or where email servers communicate with systems that might generate such patterns.
Security implications arise from the potential for this vulnerability to be exploited in email-based attacks or to cause denial of service conditions through message corruption. While no publicly available exploits are currently known, the vulnerability creates conditions that could enable attackers to manipulate email delivery behavior or potentially exploit the message splitting to create confusion in email processing systems. The issue aligns with CWE-1179 which addresses improper handling of line terminators in email protocols and represents a deviation from established SMTP protocol compliance standards.
Organizations affected by this vulnerability should prioritize upgrading to the latest released version of Dovecot to address the protocol handling inconsistency. The recommended mitigation strategy focuses on applying the vendor-supplied patch or upgrade that corrects the line ending sequence interpretation to align with RFC specifications. System administrators should also implement monitoring to detect any unusual email splitting behavior or message fragmentation patterns that might indicate exploitation attempts. The vulnerability demonstrates the critical importance of strict protocol adherence in email server implementations and highlights the potential for seemingly minor protocol deviations to cause significant operational impacts in email infrastructure.