The first thing to do is to file a
. That makes other users aware of the issue you have discovered. Include a detailed description of the problem.
Follow that up with uploading a suitable patch to your RT ticket so that others may choose to apply it. Uploading a test which proves that your patch fixes the bug is quite helpful, too.
Next, follow the procedures outlined on the CPAN FAQ:
How do I go about maintaining a module when the author is unresponsive?
How do I adopt or take over a module already on CPAN?
PAUSE: taking over