The following v3.6.19.18 fix was incomplete and is now fixed as intended: "If you pressed Space to shoot the Ninja Rope while your Worm was preparing for a jump, and your Worm became airborn before you released Space, then a second pressing of Space would be ignored; an extra press would be required to detach the initial rope (or if the rope catch was denied quickly, the rope would fire again spuriously the moment your Worm became airborn)."
For some people, PNG maps were saved without a header. At first this merely caused the terrain type (soil background) to be reset each time, but starting after v3.6.19.15 the bug prevented PNG maps from being hostable at all; after loading them and exiting from the map editor a random map would be generated.
Certain games with CPU players (e.g. the mission Water Surprise) would crash right after the piechart loading stage. (Bug introduced in v3.6.19.17)