CVE-2026-52737
MediumCVSS 5.3Exploitation Probability (EPSS)
Low risk11th percentile - higher than 11% of all known CVEs
Summary
ZEBRA prior to 4.5.0 can be slowed down by a malicious P2P peer that answers getblocks/FindBlocks with a small inventory and serves a block with coinbase height far above the local tip. The error is not attributed to the peer, causing cancellation of downloads and a 67-second sync delay. The peer is not scored or disconnected, so it can repeat the attack.
Risk Assessment
The risk includes degradation of node synchronization, potentially leading to delays in transaction processing and potential DoS attacks.
Recommendation
Upgrade ZEBRA to version 4.5.0 or later and implement peer scoring mechanisms.
Original NVD description (English source)
ZEBRA is a Zcash node written entirely in Rust. Prior to 4.5.0, a malicious unauthenticated P2P peer can answer Zebra's outbound getblocks or FindBlocks request with a small two-hash inventory and then serve a syntactically valid block whose coinbase height is far above the local chain tip. In zebrad/src/components/sync/downloads.rs, BlockDownloadVerifyError::AboveLookaheadHeightLimit originally carried only the block height and hash, so handle_block_response could not attribute the failure to the advertising peer. The error then reached the restart-worthy default path in zebrad/src/components/sync.rs, cancelling all in-flight downloads from honest peers and imposing a 67-second sync restart delay on mainnet. Because the peer was neither scored nor disconnected, the peer could repeat the cycle indefinitely with minimal bandwidth and significantly degrade synchronization without corrupting state. This issue is fixed in version 4.5.0.