iDefense has reported several integer overflow flaws in GIMP. It is presumed that these flaws could lead to arbitrary code execution if a victim opens a malicious image file.
Reproducers for some of the problems can be found in one of the corresponding upstream bugs: http://bugzilla.gnome.org/show_bug.cgi?id=453973
This was addressed via: Red Hat Enterprise Linux version 2.1 (RHSA-2007:0513) Red Hat Enterprise Linux version 3 (RHSA-2007:0513) Red Hat Enterprise Linux version 4 (RHSA-2007:0513) Red Hat Enterprise Linux version 5 (RHSA-2007:0513)