Multiple buffer overflows in (1) iso2022jp.c or (2) shiftjis.c for Courier-IMAP before 3.0.0, Courier before 0.45, and SqWebMail before 4.0.0 may allow remote attackers to execute arbitrary code "when Unicode character is out of BMP range."
https://exchange.xforce.ibmcloud.com/vulnerabilities/15434
http://www.securityfocus.com/bid/9845
http://sourceforge.net/project/shownotes.php?release_id=5767