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Date: Thu, 6 Jul 2017 13:33:36 +0200
From: Marcus Meissner <>
To: OSS Security List <>
Subject: X.Org X Server stack overflow and information leak


This issue got lost under the Qualys noise :(

	The endianess handling for X Events assumed a fixed size of X Event structures and
	had a specific 32 byte stack buffer for that. 

	However "GenericEvents" can have any size, so if the events were sent in the wrong
	endianess, this stack buffer could be overflowed easily.

	So authenticated X users could overflow the stack in the X Server and with the X 
	server usually running as root gaining root prileveges.


	An information leak out of the X server due to an uninitialized stack area when swapping
	event endianess.

Ciao, Marcus

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