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EUVD-2026-355509

fkie_cve-2026-52733

ZEBRA is a Zcash node written entirely in Rust. Prior to 4.5.0, a natural or attacker-influenced chain fork can leave stale Sapling and Orchard note-commitment subtree roots in Zebra state. In zebra-state/src/service/non_finalized_state/chain.rs, Chain::pop_tip removed a reverted tip block but did not remove subtree entries whose end_height belonged to that block, unlike the cleanup performed by pop_root. When the winning fork later finalized, the abandoned branch's stale subtree data could be written to RocksDB and survive node restarts. The corrupted history can cause z_getsubtreesbyindex consumers such as lightwalletd and light wallets to receive incorrect subtree roots, producing wallet synchronization failures or incorrect wallet state and requiring a full state rebuild for recovery. This issue is fixed in version 4.5.0.

GHSA-2gf8-q9rr-jq3h — zebrad has persistent on-disk corruption of Sapling/Orchard subtree roots after chain fork via pop_tip

Affected: crates.io: zebra-state, crates.io: zebrad

### Am I affected

You are affected if:

1. You run `zebrad` up to and including `v4.4.1`. 2. Your node participates in a network where chain forks occur (mainnet, testnet, or any network with multiple miners).

All default configurations are affected. The corruption persists across restarts because it is written to RocksDB.

### Summary

When `pop_tip` removes the tip block during a chain fork, stale Sapling and Orchard note commitment subtree root data is retained in the in-memory non-finalized state. When the chain subsequently finalizes, this stale data is written to the persistent RocksDB state. The corrupted subtree root history affects `z_getsubtreesbyindex` (used by lightwalletd for wallet synchronization) and could affect future chain verification that depends on correct subtree roots.

### Details

The non-finalized state provides two methods for removing blocks: `pop_root` (removes the oldest block during finalization) and `pop_tip` (removes the newest block during a fork revert). `pop_root` correctly cleans up note commitment subtree contributions. `pop_tip` does not: it removes the block but retains the block's subtree root contributions in the in-memory state.

When a chain fork occurs and `pop_tip` reverts the old tip, the winning fork's chain is extended. When that chain is later finalized, the stale subtree data from the reverted blocks is included in the RocksDB write batch and persisted to disk.

The `pop_root`/`pop_tip` asymmetry is specific to subtree ro…