Vulnerability Description
ZEBRA is a Zcash node written entirely in Rust. Prior to 4.5.0, a malicious block producer can terminate zebrad by placing the same shielded transaction in a non-finalized parent block and its child. In zebra-state/src/service/non_finalized_state/chain.rs, Chain::push originally inserted the transaction hash into tx_loc_by_hash and asserted uniqueness before updating shielded data and running the duplicate Sprout, Sapling, or Orchard nullifier checks. The repeated transaction therefore reached the transactions must be unique within a single chain assertion before contextual validation could reject it cleanly. Zebra release builds use panic equals abort, so the reachable assertion terminates the entire process; exploitation requires either two consecutive attacker-mined blocks or an attacker-mined child immediately after an honest block includes the attacker's shielded transaction. 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/releases/tag/v4.5.0
- https://github.com/ZcashFoundation/zebra/security/advisories/GHSA-hhm7-qrv5-h4r6
FAQ
What is CVE-2026-52739?
CVE-2026-52739 is a vulnerability with a CVSS score of 5.9 (MEDIUM). ZEBRA is a Zcash node written entirely in Rust. Prior to 4.5.0, a malicious block producer can terminate zebrad by placing the same shielded transaction in a non-finalized parent block and its child. ...
How severe is CVE-2026-52739?
CVE-2026-52739 has been rated MEDIUM with a CVSS base score of 5.9/10. Review the CVSS metrics above for detailed severity breakdown.
Is there a patch for CVE-2026-52739?
Check the references section above for vendor advisories and patch information. Review vendor security bulletins for remediation guidance.