X.Org Servers Updated To Fix Security Flaw

Peter Hutterer has issued unscheduled updates to the X.Org Server 1.13 and 1.14 release series to address a new input security vulnerability on Linux.

Coming about last week was CVE-2013-1940. Red Hat employees discovered, "An information disclosure flaw was found in the way X.org X11 server...used to register new hot-plug devices, when X.org X11 server was instructed (for that particular moment) not to receive input devices events. Formerly when registering new input device, X.org X11 server simultaneously enabled retrieval of input from the particular device (regardless of the setting). A local unsuspecting user, relying on the X.org X11 server disable input feature it to properly prohibit acquiring of events from this newly added hot-plug device, could supply a sensitive information that, due the above bug, would become available to the physically proximate attackers."

X.Org input expert and Red Hat employee Peter Hutterer ended up fixing the security problem yesterday with this patch. "So when we VT switch back and attempt to flush the input devices, we don't succeed because evdev won't return part of an event, since we were only asking for 4 bytes, we'd only get -EINVAL back. This could later cause events to be flushed that we shouldn't have gotten. This is a fix for CVE-2013-1940."

This issue affects all hotplugging-enabled X.Org Servers relying upon evdev for input devices. After committing the security fix, Hutterer released X.Org Server 1.13.4 and X.Org Server 1.14.1.

Fortunately, Peter characterizes this security issue as "lminor" within a blog post. There's more details on the issue as well in a Google+ post by David Airlie.

There's also a couple of other changes that were built up into each of these releases for the two latest xorg-server series, but nothing particularly exciting.