The imap package provides server daemons for both the IMAP (Internet Message Access Protocol) and POP (Post Office Protocol) mail access protocols.
A logic error in the CRAM-MD5 code in the University of Washington IMAP (UW-IMAP) server was discovered. When Challenge-Response Authentication Mechanism with MD5 (CRAM-MD5) is enabled, UW-IMAP does not properly enforce all the required conditions for successful authentication, which could allow remote attackers to authenticate as arbitrary users. The Common Vulnerabilities and Exposures project (cve.mitre.org) has assigned the name CAN-2005-0198 to this issue.
All users of imap should upgrade to these updated packages, which contain a backported patch and are not vulnerable to this issue.