which scale is used in Nirvana's "Love Buzz"? is this an eastern scale? how is it possible to mix an eastern scale and a western rhythm? which scale should be used in its baseline?
It's the phrygian dominant scale, whose composition is (starting from E for example's sake):
Notes: E F G# A B C D
Intervals: 1 b2 3 4 5 b6 b7
Addressing your other questions:
is this an eastern scale?
Wikipedia article says:
This scale occurs in Indian, Middle Eastern, Eastern European, Central Asian, and Flamenco music. It is common in Arabic and Egyptian music [...]
So yes it is.
how is it possible to mix an eastern scale and a western rhythm?
Like in the very track you mentioned for instance ;)) Or in Dick Dale music as a more famous example.
which scale should be used in its baseline?
I assume you ask about on top of which chords can you play this scale. You can work it out yourself by observing its third stacks, here you have an E-based reference:
E7 FMaj7 G#dim Ammaj7 Bm7b5 CMaj7#5 Dm7