=========================================================================Ubuntu Security Notice USN-2994-1
June 06, 2016

libxml2 vulnerabilities
=========================================================================
A security issue affects these releases of Ubuntu and its derivatives:

- Ubuntu 16.04 LTS
- Ubuntu 15.10
- 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 certain malformed
documents. 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. (CVE-2015-8806, CVE-2016-2073,
CVE-2016-3627, CVE-2016-3705, CVE-2016-4447)

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-2016-1762, CVE-2016-1834)

Mateusz Jurczyk 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-2016-1833, CVE-2016-1838, CVE-2016-1839)

Wei Lei and Liu Yang 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-2016-1835, CVE-2016-1837)

Wei Lei and Liu Yang 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. This issue only applied to Ubuntu 14.04 LTS, Ubuntu 15.10 and
Ubuntu 16.04 LTS. (CVE-2016-1836)

Kostya Serebryany 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-2016-1840)

It was discovered that libxml2 would load certain XML external entities. If
a user or automated system were tricked into opening a specially crafted
document, an attacker could possibly obtain access to arbitrary files or
cause resource consumption. (CVE-2016-4449)

Gustavo Grieco 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 possibly cause
libxml2 to crash, resulting in a denial of service. (CVE-2016-4483)

Update instructions:

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

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

Ubuntu 15.10:
  libxml2                         2.9.2+zdfsg1-4ubuntu0.4

Ubuntu 14.04 LTS:
  libxml2                         2.9.1+dfsg1-3ubuntu4.8

Ubuntu 12.04 LTS:
  libxml2                         2.7.8.dfsg-5.1ubuntu4.15

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

References:
  https://ubuntu.com/security/notices/USN-2994-1
  CVE-2015-8806, CVE-2016-1762, CVE-2016-1833, CVE-2016-1834,
  CVE-2016-1835, CVE-2016-1836, CVE-2016-1837, CVE-2016-1838,
  CVE-2016-1839, CVE-2016-1840, CVE-2016-2073, CVE-2016-3627,
  CVE-2016-3705, CVE-2016-4447, CVE-2016-4449, CVE-2016-4483

Package Information:
  https://launchpad.net/ubuntu/+source/libxml2/2.9.3+dfsg1-1ubuntu0.1
  https://launchpad.net/ubuntu/+source/libxml2/2.9.2+zdfsg1-4ubuntu0.4
  https://launchpad.net/ubuntu/+source/libxml2/2.9.1+dfsg1-3ubuntu4.8
  https://launchpad.net/ubuntu/+source/libxml2/2.7.8.dfsg-5.1ubuntu4.15