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USN-3258-2: Dovecot regression

11 April 2017

USN-3258-1 introduced a regression in Dovecot.



  • dovecot - IMAP and POP3 email server


USN-3258-1 intended to fix a vulnerability in Dovecot. Further investigation
revealed that only Dovecot versions 2.2.26 and newer were affected by the
vulnerability. Additionally, the change introduced a regression when Dovecot
was configured to use the "dict" authentication database. This update reverts
the change. We apologize for the inconvenience.

Original advisory details:

It was discovered that Dovecot incorrectly handled some usernames. An attacker
could possibly use this issue to cause Dovecot to hang or crash, resulting in a
denial of service.

Update instructions

The problem can be corrected by updating your system to the following package versions:

Ubuntu 16.10
Ubuntu 16.04

In general, a standard system update will make all the necessary changes.


Related notices

  • USN-3258-1: dovecot-core, dovecot-mysql, dovecot-sqlite, dovecot-imapd, dovecot-pgsql, dovecot-pop3d, dovecot-managesieved, dovecot-lucene, dovecot, dovecot-solr, dovecot-gssapi, mail-stack-delivery, dovecot-dev, dovecot-ldap, dovecot-sieve, dovecot-lmtpd