Vulnerability Description
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.
CVSS Score
MEDIUM
Related Weaknesses (CWE)
References
- https://github.com/ZcashFoundation/zebra/commit/1440b43ca7df59aca948090d45117557
- https://github.com/ZcashFoundation/zebra/commit/bc64dfe45746a86d14546a0a5a766387
- https://github.com/ZcashFoundation/zebra/pull/10647
- https://github.com/ZcashFoundation/zebra/releases/tag/v4.5.0
- https://github.com/ZcashFoundation/zebra/security/advisories/GHSA-gvjc-3w7c-92jx
FAQ
What is CVE-2026-52737?
CVE-2026-52737 is a vulnerability with a CVSS score of 5.3 (MEDIUM). 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 the...
How severe is CVE-2026-52737?
CVE-2026-52737 has been rated MEDIUM with a CVSS base score of 5.3/10. Review the CVSS metrics above for detailed severity breakdown.
Is there a patch for CVE-2026-52737?
Check the references section above for vendor advisories and patch information. Review vendor security bulletins for remediation guidance.