CVE-2011-1926: Cmu Cyrus Imap Server

Medium severity, CVSS 5.1. EPSS: 4% chance of exploitation in the next 30 days.

The STARTTLS implementation in Cyrus IMAP Server before 2.4.7 does not properly restrict I/O buffering, which allows man-in-the-middle attackers to insert commands into encrypted sessions by sending a cleartext command that is processed after TLS is in place, related to a "plaintext command injection" attack, a similar issue to CVE-2011-0411.

Affected products

• Cmu Cyrus Imap Server: up to and including 2.4.6; version 2.0.17 only; version 2.1.16 only; version 2.1.17 only; version 2.1.18 only; version 2.2.8 only; …

Published 2011-05-23. Last modified 2026-06-16.