===========================================================================
Ubuntu Security Notice USN-3183-1
February 01, 2017

gnutls26, gnutls28 vulnerabilities
===========================================================================

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

- Ubuntu 16.10
- Ubuntu 16.04 LTS
- Ubuntu 14.04 LTS
- Ubuntu 12.04 LTS

Summary:

Several security issues were fixed in GnuTLS.

Software Description:
- gnutls28: GNU TLS library
- gnutls26: GNU TLS library

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 16.10:
  libgnutls30                     3.5.3-5ubuntu1.1

Ubuntu 16.04 LTS:
  libgnutls30                     3.4.10-4ubuntu1.2

Ubuntu 14.04 LTS:
  libgnutls26                     2.12.23-12ubuntu2.6

Ubuntu 12.04 LTS:
  libgnutls26                     2.12.14-5ubuntu3.13

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

References:
  http://www.ubuntu.com/usn/usn-3183-1
  CVE-2016-7444, CVE-2016-8610, CVE-2017-5334, CVE-2017-5335,
  CVE-2017-5336, CVE-2017-5337

Package Information:
  https://launchpad.net/ubuntu/+source/gnutls28/3.5.3-5ubuntu1.1
  https://launchpad.net/ubuntu/+source/gnutls28/3.4.10-4ubuntu1.2
  https://launchpad.net/ubuntu/+source/gnutls26/2.12.23-12ubuntu2.6
  https://launchpad.net/ubuntu/+source/gnutls26/2.12.14-5ubuntu3.13