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Old 25th May 2013
shep shep is offline
Real Name: Scott
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Join Date: May 2008
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Posts: 1,503
Default Protocol handling issues in X Window System client libraries

Quote:
Ilja van Sprundel, a security researcher with IOActive, has discovered
a large number of issues in the way various X client libraries handle
the responses they receive from servers, and has worked with X.Org's
security team to analyze, confirm, and fix these issues.

Most of these issues stem from the client libraries trusting the server
to send correct protocol data, and not verifying that the values will
not overflow or cause other damage. Most of the time X clients & servers
are run by the same user, with the server more privileged from the clients,
so this is not a problem, but there are scenarios in which a privileged
client can be connected to an unprivileged server, for instance, connecting
a setuid X client (such as a screen lock program) to a virtual X server
(such as Xvfb or Xephyr) which the user has modified to return invalid
data, potentially allowing the user to escalate their privileges.
Oss-security

The CVE's are almost TNTC (Too numerous to count) and I would be very impressed if OpenBSD's xorg implementation escapes unscathed.
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