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Ubuntu Security Notice USN-3235-1
March 16, 2017

libxml2 vulnerabilities
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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 libxml2.

Software Description:
- libxml2: GNOME XML library

Details:

It was discovered that libxml2 incorrectly handled format strings. If a
user or automated system were tricked into opening a specially crafted
document, an attacker could possibly cause libxml2 to crash, resulting in a
denial of service. This issue only affected Ubuntu 12.04 LTS, Ubuntu 14.04
LTS, and Ubuntu 16.04 LTS. (CVE-2016-4448)

It was discovered that libxml2 incorrectly handled certain malformed
documents. If a user or automated system were tricked into opening a
specially crafted document, an attacker could cause libxml2 to crash,
resulting in a denial of service, or possibly execute arbitrary code.
(CVE-2016-4658)

Nick Wellnhofer discovered that libxml2 incorrectly handled certain
malformed documents. If a user or automated system were tricked into
opening a specially crafted document, an attacker could cause libxml2 to
crash, resulting in a denial of service, or possibly execute arbitrary
code. (CVE-2016-5131)

Update instructions:

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

Ubuntu 16.10:
  libxml2                         2.9.4+dfsg1-2ubuntu0.1

Ubuntu 16.04 LTS:
  libxml2                         2.9.3+dfsg1-1ubuntu0.2

Ubuntu 14.04 LTS:
  libxml2                         2.9.1+dfsg1-3ubuntu4.9

Ubuntu 12.04 LTS:
  libxml2                         2.7.8.dfsg-5.1ubuntu4.17

After a standard system update you need to reboot your computer to make
all the necessary changes.

References:
  http://www.ubuntu.com/usn/usn-3235-1
  CVE-2016-4448, CVE-2016-4658, CVE-2016-5131

Package Information:
  https://launchpad.net/ubuntu/+source/libxml2/2.9.4+dfsg1-2ubuntu0.1
  https://launchpad.net/ubuntu/+source/libxml2/2.9.3+dfsg1-1ubuntu0.2
  https://launchpad.net/ubuntu/+source/libxml2/2.9.1+dfsg1-3ubuntu4.9
  https://launchpad.net/ubuntu/+source/libxml2/2.7.8.dfsg-5.1ubuntu4.17