nimiq-primitives: Panic DoS in trie chunk processing via ROOT-keyed item
A remote, unauthenticated denial-of-service vulnerability in MerkleRadixTrie::put_chunk allows any state-sync peer to crash any node performing state synchronization (freshly joining nodes and recovering nodes). A malicious peer can respond to a RequestChunk with a ResponseChunk::Chunk whose first TrieItem.key is the empty (ROOT) key. The chunk passes sorting, range, and Merkle-proof validation, but when put_raw tries to store a value at the root node, it calls TrieNode::put_value(…).unwrap(), which returns Err(RootCantHaveValue) and …