libXcursor before 1.1.15 has various integer overflows that could lead to heap buffer overflows when processing malicious cursors, e.g., with programs like GIMP. It is also possible that an attack vector exists against the related code in cursor/xcursor.c in Wayland through 1.14.0.
The product performs a calculation that can produce an integer overflow or wraparound when the logic assumes that the resulting value will always be larger than the original value. This occurs when an integer value is incremented to a value that is too large to store in the associated representation. When this occurs, the value may become a very small or negative number.