ZcashFoundation Zebra/Zebra State up to 4.4.x Non Finalized State chain.rs Chain::push assertion

Summaryinfo

A vulnerability described as critical has been identified in ZcashFoundation Zebra and Zebra State up to 4.4.x. Affected by this issue is the function Chain::push of the file zebra-state/src/service/non_finalized_state/chain.rs of the component Non Finalized State. Executing a manipulation can lead to assertion. This vulnerability is tracked as CVE-2026-52739. The attack can be launched remotely. No exploit exists.

Detailsinfo

A vulnerability classified as critical was found in ZcashFoundation Zebra and Zebra State up to 4.4.x. This vulnerability affects the function Chain::push of the file zebra-state/src/service/non_finalized_state/chain.rs of the component Non Finalized State. The manipulation with an unknown input leads to a assertion vulnerability. The CWE definition for the vulnerability is CWE-617. The product contains an assert() or similar statement that can be triggered by an attacker, which leads to an application exit or other behavior that is more severe than necessary. As an impact it is known to affect availability. CVE summarizes:

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.

The advisory is available at github.com. This vulnerability was named CVE-2026-52739 since 06/08/2026. The exploitation appears to be easy. The attack can be initiated remotely. No form of authentication is required for a successful exploitation. Technical details are known, but there is no available exploit.

Upgrading to version 4.5.0 eliminates this vulnerability.

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Productinfo

Vendor

• ZcashFoundation

Name

• Zebra
• Zebra State

Version

• 4.0
• 4.1
• 4.2
• 4.3
• 4.4

Website

• Product: https://github.com/ZcashFoundation/zebra/

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