Ubuntu Security Notice USN-3061-1

15th August, 2016

openssh vulnerabilities

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

• Ubuntu 16.04 LTS
• Ubuntu 14.04 LTS
• Ubuntu 12.04 LTS

Summary

Several security issues were fixed in OpenSSH.

Software description

• openssh
  – secure shell (SSH) for secure access to remote machines

Details

Eddie Harari discovered that OpenSSH incorrectly handled password hashing
when authenticating non-existing users. A remote attacker could perform a
timing attack and enumerate valid users. (CVE-2016-6210)

Tomas Kuthan, Andres Rojas, and Javier Nieto discovered that OpenSSH did
not limit password lengths. A remote attacker could use this issue to cause
OpenSSH to consume resources, leading to a denial of service.
(CVE-2016-6515)

Update instructions

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

Ubuntu 16.04 LTS:

openssh-server

1:7.2p2-4ubuntu2.1

Ubuntu 14.04 LTS:

openssh-server

1:6.6p1-2ubuntu2.8

Ubuntu 12.04 LTS:

openssh-server

1:5.9p1-5ubuntu1.10

To update your system, please follow these instructions:
https://wiki.ubuntu.com/Security/Upgrades.

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

References

CVE-2016-6210,

CVE-2016-6515