It was found that vncconnectionservermessage() and vnccolormapset() functions do not check for integer overflow properly, leading to a malicious server being able to overwrite parts of the client memory, possibly leading to remote code execution under privileges of user running the VNC client.
Upstream bug:
https://bugzilla.gnome.org/showbug.cgi?id=778050
Upstream patch:
https://git.gnome.org/browse/gtk-vnc/commit/?id=c8583fd3783c5b811590
gtk-vnc before 0.7.0 does not properly check boundaries of subrectangle-containing tiles, which allows remote servers to execute arbitrary code via the src x, y coordinates in a crafted (1) rre, (2) hextile, or (3) copyrect tile.