acpid is a daemon that dispatches ACPI (Advanced Configuration and Power Interface) events to user-space programs.
It was discovered that acpid could create its log file ("/var/log/acpid") with random permissions on some systems. A local attacker could use this flaw to escalate their privileges if the log file was created as world-writable and with the setuid or setgid bit set. (CVE-2009-4033)
Please note that this flaw was due to a Red Hat-specific patch (acpid-1.0.4-fd.patch) included in the Red Hat Enterprise Linux 5 acpid package.
Users are advised to upgrade to this updated package, which contains a backported patch to correct this issue.