Nimiq is a Rust implementation of the Nimiq Proof-of-Stake protocol based on the Albatross consensus algorithm. Prior to 1.6.0, a malicious state-sync peer can crash a syncing node by sending a crafted TrieChunk proof containing two TrieProofNode values with identical keys. TrieProof::verify calls TrieProofNode::child_index in primitives/src/trie/trie_proof_node.rs, where is_prefix_of accepts equal keys and KeyNibbles::get is called at the key length, returns None, and is unconditionally unwrapped. Untrusted ResponseChunk data reaches commit_chunks, put_chunk, and proof.verify before cryptographic proof validation, so the attacker does not need a valid proof. Exploitation requires the attacker to be selected as the victim's sync peer during state sync, and the resulting panic is transient…