[USN-3881-2] Dovecot vulnerability

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Ubuntu Security Notice USN-3881-2
February 05, 2019

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

- Ubuntu 12.04 ESM

Summary:

Dovecot could be made to expose sensitive information over the network.

Software Description:
- dovecot: IMAP and POP3 email server

Details:

USN-3881-1 fixed a vulnerability in Dovecot. This update provides
the corresponding update for Ubuntu 12.04 ESM.

Original advisory details:

 It was discovered that Dovecot incorrectly handled client
 certificates. A remote attacker in possession of a valid certificate
 with an empty username field could possibly use this issue to
 impersonate other users.

Update instructions:

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

Ubuntu 12.04 ESM:
  dovecot-core                    1:2.0.19-0ubuntu2.6

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

References:
  https://usn.ubuntu.com/usn/usn-3881-2
  https://usn.ubuntu.com/usn/usn-3881-1
  CVE-2019-3814