IS $LOGSPACE\subsetneq QMA$ an open problem?
Widely open, I can tell. $\mathrm{QMA}\subseteq\mathrm{PP}$ is known. But, $\mathrm{PP}$ has been only separated from $\mathrm{uniform}$-$\mathrm{TC}^0$ up to now. So, even the stronger claim $\mathrm{L}=\mathrm{PP}$ is still unrefutable.

From the Wikipedia article https://en.wikipedia.org/wiki/PP_(complexity)#PP_compared_to_other_complexity_classes, $\mathrm{PP}$ strictly contains $\mathrm{TC}^0$, the class of constant-depth, unbounded-fan-in uniform boolean circuits with majority gates. (Allender 1996, as cited in Burtschick 1999)

Allender, E. (1996). "A note on uniform circuit lower bounds for the counting hierarchy". Proceedings 2nd International Computing and Combinatorics Conference (COCOON). Lecture Notes in Computer Science. 1090. Springer-Verlag. pp. 127–135

Burtschick, Hans-Jörg; Vollmer, Heribert (1999). "Lindström Quantifiers and Leaf Language Definability". ECCC TR96-005