7.5 - USN-260-1

A security issue affects the following Ubuntu releases:

Ubuntu 4.10 (Warty Warthog) Ubuntu 5.04 (Hoary Hedgehog) Ubuntu 5.10 (Breezy Badger)

The following packages are affected:

flex gpc-2.1-3.3 gpc-2.1-3.4

The problem can be corrected by upgrading the affected package to the following versions:

Ubuntu 4.10:

flex: 2.5.31-26ubuntu1.2
gpc-2.1-3.3: 2:3.3.4.20040516-9ubuntu5.1
gpc-2.1-3.4: 3.4.2-2ubuntu1.1

Ubuntu 5.04:

flex: 2.5.31-31ubuntu0.5.04.1
gpc-2.1-3.3: 2:3.3.5.20040516-8ubuntu2.1
gpc-2.1-3.4: 3.4.3-9ubuntu4.1

Ubuntu 5.10:

flex: 2.5.31-31ubuntu0.5.10.1
gpc-2.1-3.4: 3.4.4-6ubuntu8.1

In general, a standard system upgrade is sufficient to effect the necessary changes.

Details follow:

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).