Red Hat Security Advisory 2011-0859 - The cyrus-imapd packages contain a high-performance mail server with IMAP, POP3, NNTP, and Sieve support. It was discovered that cyrus-imapd did not flush the received commands buffer after switching to TLS encryption for IMAP, LMTP, NNTP, and POP3 sessions. A man-in-the-middle attacker could use this flaw to inject protocol commands into a victim's TLS session initialization messages. This could lead to those commands being processed by cyrus-imapd, potentially allowing the attacker to steal the victim's mail or authentication credentials. Various other issues were also addressed.
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