CVE-2026-52736
HighCVSS 8.7Exploitation Probability (EPSS)
Low risk37th percentile - higher than 37% of all known CVEs
Summary
ZEBRA before version 4.5.0 has a vulnerability allowing a remote unauthenticated P2P peer to stall a node by racing an invalid block body against the valid canonical body for the same block header hash. This causes the node to reject the valid body and remain stuck one height behind until restart or reorganization. The issue is fixed in version 4.5.0.
Risk Assessment
The risk includes remote stalling of node synchronization, potentially causing delays in transaction processing and loss of network consistency. The attack requires no authentication.
Recommendation
Upgrade ZEBRA to version 4.5.0 or later. Also monitor nodes for synchronization delays.
Original NVD description (English source)
ZEBRA is a Zcash node written entirely in Rust. Prior to 4.5.0, a remote unauthenticated P2P peer can stall a Zebra node by racing an invalid block body against the valid canonical body for the same block header hash. ZIP-244 permits the attacker to mutate coinbase scriptSig authentication data while retaining the transaction identifiers, merkle root, and block header hash, so the poisoned body fails later commitment validation but shares the canonical hash. In zebra-state/src/service.rs, queue_and_commit_to_non_finalized_state recorded the hash in non_finalized_block_write_sent_hashes before contextual validation completed and did not remove it when the write task rejected the body. When the honest body later arrived, the cached hash caused KnownBlock::WriteChannel duplicate handling to suppress it, leaving the node stuck one height behind until restart or reorganization. This issue is fixed in version 4.5.0.