Advisory Published
Updated

REDHAT-BUG-842841

First published: Tue Jul 24 2012(Updated: )

From the upstream announcement [1]: A vulnerability has been found in the X11R6 font server code in the handling of the SetEventMask request in xfs - if an invalid mask is specified, it passes that bad mask to the SendErrToClient() function for returning to the client in the error message. Unfortunately, SendErrToClient() expects a pointer, but was being passed the raw mask value, causing it to use the mask as a pointer, either segfaulting (if that happened to be an invalid pointer), or returning whatever data happened to be accessible in the 4 bytes at the address specified by the mask value. X11R6 through X11R6.6 appear to be vulnerable. The fix shown below was introduced by XFree86 in their 3.3.3 release as part of the commit for: Prototype/ansification cleanup for Xserver/XIE, xfs, fontlib, mkfontdir, and fix some bugs found along the way (#2103, Thomas Dickey). X11R6.7 incorporated the XFree86 changes, and thus X11R6.7 and later releases from X.Org are not vulnerable. [1] <a href="http://lists.freedesktop.org/archives/xorg-announce/2012-July/002040.html">http://lists.freedesktop.org/archives/xorg-announce/2012-July/002040.html</a> Statement: Not vulnerable. This issue did not affect the versions of xorg-x11-xfs as shipped with Red Hat Enterprise Linux 5. It does not affect Red Hat Enterprise Linux 6 as it no longer uses or provides the XFS font server.

Affected SoftwareAffected VersionHow to fix
X11 Fonts Utilities>=X11R6<=X11R6.6

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Frequently Asked Questions

  • What is the severity of REDHAT-BUG-842841?

    The severity of REDHAT-BUG-842841 is classified as having a medium impact due to potential disruptions in the X11R6 font server's functionality.

  • How do I fix REDHAT-BUG-842841?

    To fix REDHAT-BUG-842841, upgrade to a version of X11R6 that has addressed this vulnerability, ideally to the latest available release.

  • What systems are affected by REDHAT-BUG-842841?

    The systems affected by REDHAT-BUG-842841 include those running the X.Org X11R6 version prior to X11R6.6.

  • What potential risks are associated with REDHAT-BUG-842841?

    The potential risks associated with REDHAT-BUG-842841 include denial of service and unexpected behavior in the X11R6 font server.

  • Is there a workaround for REDHAT-BUG-842841?

    There are no specific workarounds for REDHAT-BUG-842841; applying the necessary updates is recommended.

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