USN-1308-1: bzip2 vulnerability

14 December 2011

bzip2 vulnerability

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

  • Ubuntu 11.10
  • Ubuntu 11.04
  • Ubuntu 10.10
  • Ubuntu 10.04 LTS
  • Ubuntu 8.04 LTS


Executables compressed by bzexe could be made to run programs as your login.

Software Description

  • bzip2 - high-quality block-sorting file compressor - utilities


vladz discovered that executables compressed by bzexe insecurely create temporary files when they are ran. A local attacker could exploit this issue to execute arbitrary code as the user running a compressed executable.

Update instructions

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

Ubuntu 11.10
bzip2 - 1.0.5-6ubuntu1.11.10.1
Ubuntu 11.04
bzip2 - 1.0.5-6ubuntu1.11.04.1
Ubuntu 10.10
bzip2 - 1.0.5-4ubuntu1.1
Ubuntu 10.04 LTS
bzip2 - 1.0.5-4ubuntu0.2
Ubuntu 8.04 LTS
bzip2 - 1.0.4-2ubuntu4.2

To update your system, please follow these instructions:

In general, a standard system update will make all the necessary changes to the bzexe utility. If you have previously used bzexe to compress any executables, they need to be recompressed using the updated version.