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Ubuntu Security Notice USN-2710-2
August 18, 2015

openssh regression
============================================================================

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

- Ubuntu 15.04
- Ubuntu 14.04 LTS
- Ubuntu 12.04 LTS

Summary:

USN-2710-1 introduced a regression in OpenSSH.

Software Description:
- openssh: secure shell (SSH) for secure access to remote machines

Details:

USN-2710-1 fixed vulnerabilities in OpenSSH. The upstream fix for
CVE-2015-5600 caused a regression resulting in random authentication
failures in non-default configurations. This update fixes the problem.

Original advisory details:

 Moritz Jodeit discovered that OpenSSH incorrectly handled usernames when
 using PAM authentication. If an additional vulnerability were discovered in
 the OpenSSH unprivileged child process, this issue could allow a remote
 attacker to perform user impersonation. (CVE number pending)
  Moritz Jodeit discovered that OpenSSH incorrectly handled context memory
 when using PAM authentication. If an additional vulnerability were
 discovered in the OpenSSH unprivileged child process, this issue could
 allow a remote attacker to bypass authentication or possibly execute
 arbitrary code. (CVE number pending)
  Jann Horn discovered that OpenSSH incorrectly handled time windows for
 X connections. A remote attacker could use this issue to bypass certain
 access restrictions. (CVE-2015-5352)
  It was discovered that OpenSSH incorrectly handled keyboard-interactive
 authentication. In a non-default configuration, a remote attacker could
 possibly use this issue to perform a brute-force password attack.
 (CVE-2015-5600)

Update instructions:

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

Ubuntu 15.04:
  openssh-server                  1:6.7p1-5ubuntu1.3

Ubuntu 14.04 LTS:
  openssh-server                  1:6.6p1-2ubuntu2.3

Ubuntu 12.04 LTS:
  openssh-server                  1:5.9p1-5ubuntu1.7

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

References:
  http://www.ubuntu.com/usn/usn-2710-2
  http://www.ubuntu.com/usn/usn-2710-1
  https://launchpad.net/bugs/1485719

Package Information:
  https://launchpad.net/ubuntu/+source/openssh/1:6.7p1-5ubuntu1.3
  https://launchpad.net/ubuntu/+source/openssh/1:6.6p1-2ubuntu2.3
  https://launchpad.net/ubuntu/+source/openssh/1:5.9p1-5ubuntu1.7