I'd say it's quite possible that there are, as there is precedent for this in well-known Amazonian peoples.
The Wari' are a fairly tiny ethnic group, numbering 2,721 in 2006 and inhabiting only seven villages. However, they are well known for their once cannibalistic ways.
Historically, the Wari’ people practiced two types of cannibalism - exocannibalism (eating foreigners) and endocannibalism (eating fellow Wari’. Captured enemies or trespassing foreigners were roasted and eaten voraciously with the hands, in stereotypical cannibal fashion.
However, they also practiced a more peaceful, benign kind of cannibalism. In a show of deep respect, dead Wari' were eaten in silence and mourning, often partially putrefied too. In any case, all varieties of cannibalism were stamped out by Christian missionaries in the ‘60s.
That being said, scores of Amazonian tribes are still shrouded in mystery. As of 2007, Brazil alone was home to 67 uncontacted tribes.
I consider it fully plausible, if not likely, that at least some of the 100+ uncontacted peoples of the Amazon rainforest practice some form of cannibalism.