A vulnerability was found in X.Org. This security flaw occurs becuase the swap handler for the XTestFakeInput request of the XTest extension may corrupt the stack if GenericEvents with lengths larger than 32 bytes are sent through a the XTestFakeInput request. This issue can lead to local privileges elevation on systems where the X server is running privileged and remote code execution for ssh X forwarding sessions. This issue does not affect systems where client and server use the same byte order.