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Ubuntu Security Notice USN-3183-2
March 20, 2017

gnutls26 vulnerability
===========================================================================

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

- Ubuntu 14.04 LTS
- Ubuntu 12.04 LTS

Summary:

GnuTLS could be made to hang if it received specially crafted network
traffic.

Software Description:
- gnutls26: GNU TLS library

Details:

USN-3183-1 fixed CVE-2016-8610 in GnuTLS in Ubuntu 16.04 LTS and Ubuntu
16.10. This update provides the corresponding update for Ubuntu 12.04 LTS
and Ubuntu 14.04 LTS.

Original advisory details:

 Stefan Buehler discovered that GnuTLS incorrectly verified the serial
 length of OCSP responses. A remote attacker could possibly use this issue
 to bypass certain certificate validation measures. This issue only applied
 to Ubuntu 16.04 LTS. (CVE-2016-7444)
  Shi Lei discovered that GnuTLS incorrectly handled certain warning alerts.
 A remote attacker could possibly use this issue to cause GnuTLS to hang,
 resulting in a denial of service. This issue has only been addressed in
 Ubuntu 16.04 LTS and Ubuntu 16.10. (CVE-2016-8610)
  It was discovered that GnuTLS incorrectly decoded X.509 certificates with a
 Proxy Certificate Information extension. A remote attacker could use this
 issue to cause GnuTLS to crash, resulting in a denial of service, or
 possibly execute arbitrary code. This issue only affected Ubuntu 16.04 LTS
 and Ubuntu 16.10. (CVE-2017-5334)
  It was discovered that GnuTLS incorrectly handled certain OpenPGP
 certificates. A remote attacker could possibly use this issue to cause
 GnuTLS to crash, resulting in a denial of service, or possibly execute
 arbitrary code. (CVE-2017-5335, CVE-2017-5336, CVE-2017-5337)

Update instructions:

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

Ubuntu 14.04 LTS:
  libgnutls26                     2.12.23-12ubuntu2.7

Ubuntu 12.04 LTS:
  libgnutls26                     2.12.14-5ubuntu3.14

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

References:
  http://www.ubuntu.com/usn/usn-3183-2
  http://www.ubuntu.com/usn/usn-3183-1
  CVE-2016-8610

Package Information:
  https://launchpad.net/ubuntu/+source/gnutls26/2.12.23-12ubuntu2.7
  https://launchpad.net/ubuntu/+source/gnutls26/2.12.14-5ubuntu3.14