A quick Google doesn't say anything. Reading at the wikipedia article it seems like it is but I am not sure.
"Brown" bread usually means a type of bread made either with whole wheat flour or a mixture of whole wheat flour and white wheat flour. Sometimes gluten free bread products are called "brown bread" too - these may be made with a mixture of flours.
Bread, "brown" or white, leavened or not, is usually vegan. The basic ingredients are
- flour (which will most likely, but not certainly, be vegan)
- yeast (a unicellular microorganism significantly less complex than any plant)
But it may sometimes be enriched with butter or other dairy products or honey, or have a coating that contains egg. Vitamins and minerals, preservatives and other trace ingredients may also be added, so you will need to check the ingredients list and suitability labelling, or contact the maker if this information is not available.