The Dovecot update issued as DSA-3828-1 introduced a regression, this update reverts the backported patch. Further analysis by the Dovecot team has shown that only versions starting from 2.2.26 are affected. For reference, the original advisory text follows. It was discovered that the Dovecot email server is vulnerable to a denial of service attack. When the dict passdb and userdb are used for user authentication, the username sent by the IMAP/POP3 client is sent through var_expand to perform %variable expansion. Sending specially crafted %variable fields could result in excessive memory usage causing the process to crash .