udev provides a user-space API and implements a dynamic device directory, providing only the devices present on the system. udev replaces devfs in order to provide greater hot plug functionality. Netlink is a datagram oriented service, used to transfer information between kernel modules and user-space processes.
It was discovered that udev did not properly check the origin of Netlink messages. A local attacker could use this flaw to gain root privileges via a crafted Netlink message sent to udev, causing it to create a world-writable block device file for an existing system block device (for example, the root file system). (CVE-2009-1185)
Red Hat would like to thank Sebastian Krahmer of the SUSE Security Team for responsibly reporting this flaw.
Users of udev are advised to upgrade to these updated packages, which contain a backported patch to correct this issue. After installing the update, the udevd daemon will be restarted automatically.