To be clear, posting your work to BandLab is not exactly identical to using a creative commons license, although it does involve granting various licenses. It is unfortunate that BandLab has decided to use their own jargon (forking) to describe the process of inviting collaboration. It is even more unfortunate that users will not immediately recognize that this process, in addition to inviting "collaboration," effectively licenses the creation of derivative works. Once you give someone permission to alter your work, he has the right to copyright his variation in its own right, and lacking specific language in the license, you largely lose any ability to restrict his use or publication of the derivative work. In countries where a non-transferable "moral right" to maintain the artistic integrity of your work is recognized, you may be able to limit egregiously damaging modification, but in US law at least, moral rights are only recognized for certain works of visual arts.
Whether BandLab will recognize your concerns is largely an issue of company policy, but arguably the work once altered under the license terms on their site will probably be considered to be a derivative work created under a valid license which you have no right to rescind. They may remove it from their site, but the author who in good faith (at least to his belief that he had a valid license) messes up your song will likely be able to do anything he wants with his version for the duration of his newly minted copyright.
If you have not spent an adequate amount of time reading and understanding the terms of service and related binding legal contracts issued by various online posting sites, you are well advised not to post your material on them.
Rather than repeat an earlier post on this and other issues see:
http://forum.cakewalk.com/FindPost/3742329