Source code for Symantec's pcAnywhere has been borrowed.. . back in 2006, but they have finally had time to get around to that and now are advising their clients to disable the software.
Why ? What is the security problem with having your source code exposed ? There are many users, including myself, who use software for which the source code is published all over the Internet.
In this case it seems like Symantec had a security breach that they were aware of and only decided to address because they heard about a leak of their source code. Something obviously doesn't add up, either they don't bother to patch their products, even when they know it's insecure OR they have their reasons for making insecure products..
Moral of the story, using non-Free software is a very big security issue. You never know what it really does nor who it's intended to really serve.