CentOS Errata and Security Advisory CESA-2012:0939
X.Org is an open source implementation of the X Window System. It provides the basic low-level functionality that full-fledged graphical user interfaces are designed upon.
A flaw was found in the way the X.Org server handled lock files. A local user with access to the system console could use this flaw to determine the existence of a file in a directory not accessible to the user, via a symbolic link attack. (CVE-2011-4028)
A race condition was found in the way the X.Org server managed temporary lock files. A local attacker could use this flaw to perform a symbolic link attack, allowing them to make an arbitrary file world readable, leading to the disclosure of sensitive information. (CVE-2011-4029)
Red Hat would like to thank the researcher with the nickname vladz for reporting these issues.
This update also fixes the following bugs:
Prior to this update, the KDE Display Manager (KDM) could pass invalid 24bpp pixmap formats to the X server. As a consequence, the X server could unexpectedly abort. This update modifies the underlying code to pass the correct formats. (BZ#651934, BZ#722860)
Prior to this update, absolute input devices, like the stylus of a graphic tablet, could become unresponsive in the right-most or bottom-most screen if the X server was configured as a multi-screen setup through multiple "Device" sections in the xorg.conf file. This update changes the screen crossing behavior so that absolute devices are always mapped across all screens. (BZ#732467)
Prior to this update, the misleading message "Session active, not inhibited, screen idle. If you see this test, your display server is broken and you should notify your distributor." could be displayed after resuming the system or re-enabling the display, and included a URL to an external web page. This update removes this message. (BZ#748704)
Prior to this update, the erroneous input handling code of the Xephyr server disabled screens on a screen crossing event. The focus was only on the screen where the mouse was located and only this screen was updated when the Xephyr nested X server was configured in a multi-screen setup. This update removes this code and Xephyr now correctly updates screens in multi-screen setups. (BZ#757792)
Prior to this update, raw events did not contain relative axis values. As a consequence, clients which relied on relative values for functioning did not behave as expected. This update sets the values to the original driver values instead of the already transformed values. Now, raw events contain relative axis values as expected. (BZ#805377)
All users of xorg-x11-server are advised to upgrade to these updated packages, which correct these issues. All running X.Org server instances must be restarted for this update to take effect.
Merged security bulletin from advisories: http://lists.centos.org/pipermail/centos-announce/2012-July/018722.html
Affected packages: xorg-x11-server xorg-x11-server-Xdmx xorg-x11-server-Xephyr xorg-x11-server-Xnest xorg-x11-server-Xorg xorg-x11-server-Xvfb xorg-x11-server-common xorg-x11-server-devel xorg-x11-server-source
Upstream details at: https://rhn.redhat.com/errata/RHSA-2012-0939.html