xorg-server -- Multiple input validation failures in X server extensions

The X.org project reports:

All theses issuses can lead to local privileges elevation on systems where the X server is running privileged.

The handler for the XkbSetNames request does not validate the request length before accessing its contents.

An integer underflow exists in the handler for the XIChangeHierarchy request.

An integer underflow exist in the handler for the XkbSelectEvents request.

An integer underflow exist in the handler for the CreateRegister request of the X record extension.

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