Red Hat is aware of this issue and is tracking it via the following bug: https://bugzilla.redhat.com/CVE-2009-4021
The Linux kernel packages as shipped with Red Hat Enterprise Linux 3 and 4 do not include support for FUSE, and therefore are not affected by this issue.
It was addressed in Red Hat Enterprise Linux 5 via https://rhn.redhat.com/errata/RHSA-2010-0046.html
A future kernel update for Red Hat Enterprise MRG will address this flaw.
CVSS v2 metrics
NOTE: The following CVSS v2 metrics and score provided are preliminary and subject to review.
Find out more about Red Hat support for the Common Vulnerability Scoring System (CVSS).
Red Hat Security Errata
|MRG Grid for RHEL 5 Server (kernel-rt)||RHSA-2010:0041||2010-01-21|
|Red Hat Enterprise Linux 5 (kernel)||RHSA-2010:0046||2010-01-19|