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Ubuntu Security Notice USN-3556-2
February 01, 2018

dovecot vulnerabilities
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A security issue affects these releases of Ubuntu and its derivatives:

- Ubuntu 12.04 ESM

Summary:

Several security issues were fixed in Dovecot.

Software Description:
- dovecot: IMAP and POP3 email server

Details:

USN-3556-1 fixed vulnerabilities in Dovecot. This update
provides the corresponding update for Ubuntu 12.04 ESM.

It was discovered that Dovecot incorrectly handled certain
authentications. An attacker could possibly use this to bypass
authentication and access sensitive information. (CVE-2013-6171)

Original advisory details:

 It was discovered that Dovecot incorrectly handled certain
authentications.
 An attacker could possibly use this to cause a denial of service.
(CVE-2017-15132)

Update instructions:

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

Ubuntu 12.04 ESM:
  dovecot-core                    1:2.0.19-0ubuntu2.4

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

References:
  https://www.ubuntu.com/usn/usn-3556-2
  https://www.ubuntu.com/usn/usn-3556-1
  CVE-2013-6171, CVE-2017-15132