QA-07: Unbounded Accumulation of Future Round Votes in VoteState

Summary

VoteState::process_vote accepts votes for any round greater than or equal to earliest_round without applying a maximum future-round window.

Vulnerability details

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if round < self.earliest_round {
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    return (None, ret_commands);
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}
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let round_state = self.pending_votes.entry(round).or_default();
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let node_votes = round_state.node_votes.entry(*author).or_default();
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node_votes.insert(vote_msg.sig);
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let round_pending_votes = round_state.pending_votes.entry(vote).or_default();
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round_pending_votes.insert(*author, vote_msg.sig);

Impact

Future-round entries can accumulate in pending_votes indefinitely when no QC advances the window. A malicious validator can exploit that to drive unbounded memory growth.

Recommendation

Apply round-window limits and treat duplicate or obviously abusive future-round votes as evidence or drop conditions.