The Slavic and Baltic words might still be borrowings from Germanic – phonetically there's no problem with it – but since the word was not attested in either Gothic or Old High German (the two main sources of Germanic loans in PS), it's better to guess the word was native in order to avoid "proliferation of essences" by creating more reconstructions and assumptions. The Caucasian cognates are most deffinitely from Germanic though, and the only possible source could be Gothic (I think); so it's not that easy with the Slavic and Baltic ones. Anyways, comparative linguistics often needs a time machine to resolve some problems such as this one. We'll never know for sure.
According to the source TzarSimenon posted, Western Balkan and Western Sredna Gora only.