USN-260-1: flex vulnerability

7 March 2006

flex vulnerability

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

  • Ubuntu 5.10
  • Ubuntu 5.04
  • Ubuntu 4.10

Software Description

Details

Chris Moore discovered a buffer overflow in a particular class of lexicographical scanners generated by flex. This could be exploited to execute arbitrary code by processing specially crafted user-defined input to an application that uses a flex scanner for parsing.

This flaw particularly affects gpc, the GNU Pascal Compiler. A potentially remote attacker could exploit this by tricking an user or automated system into compiling a specially crafted Pascal source code file.

Please note that gpc is not officially supported in Ubuntu (it is in the ‘universe’ component of the archive). However, this affects you if you use a customized version built from the gcc-3.3 or gcc-3.4 source package (which is supported).

Update instructions

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

Ubuntu 5.10
flex
gpc-2.1-3.3
gpc-2.1-3.4
Ubuntu 5.04
flex
gpc-2.1-3.3
gpc-2.1-3.4
Ubuntu 4.10
flex
gpc-2.1-3.3
gpc-2.1-3.4

To update your system, please follow these instructions: https://wiki.ubuntu.com/Security/Upgrades.

References