Wikimedia Bugzilla is closed!

Having a problem with including one template within another. Relevant code is as
follows:

{{Exercise
Navbox|course={{{course}}}|chapter={{{chapter}}}|section={{{section}}}|foo=bar}}

This is part of "Template:Exercise" on my MediaWiki install. A user calls
{{Exercise}} with the given parameters, which are then passed to {{Exercise
Navbox}} as shown (among other places, hence the doubling up. However, MediaWiki
reads the first two }} in '{{{course}}}' not as a parameter call but as a
closing of the original '{{Exercise Navbox' code. THis results in '{{{course'
being passed to the course variable in the {{Exercise Navbox}} call and the
rest, '}|chapter={{{chapter}}}|section={{{section}}}|foo=bar}}' gets displayed
as simple text.

Can this be fixed?