Here's a patch addressing the potential vulnerability as reported. The patch should also bring the implementation up to date with the most recent standards around header names and values.

> There could be potential for breaking compatibility if people are intentionally sending values with folded lines (obsoleted by the new HTTP RFC).

I think I'm okay with this given line folding seems to have been implemented by passing multiple value parameters (folding was automatically taken care of by the library).

I don't think that this should be merged into anything pre 3.5 as safeguarding /should/ be accounted for by the developer, so I don't think I'd regard this as a high risk security issue. I'm definitely open to debate on that though.