CVE-2023-3138

A vulnerability was found in libX11. The security flaw occurs because the
functions in src/InitExt.c in libX11 do not check that the values provided
for the Request, Event, or Error IDs are within the bounds of the arrays
that those functions write to, using those IDs as array indexes. They trust
that they were called with values provided by an Xserver adhering to the
bounds specified in the X11 protocol, as all X servers provided by X.Org
do. As the protocol only specifies a single byte for these values, an
out-of-bounds value provided by a malicious server (or a malicious
proxy-in-the-middle) can only overwrite other portions of the Display
structure and not write outside the bounds of the Display structure itself,
possibly causing the client to crash with this memory corruption.