Zebra: Cached Mempool Verification Bypasses Consensus Rules for Ahead-of-Tip Blocks

ZEBRA is a Zcash node written entirely in Rust. Prior to zebrad version 4.3.1 and zebra-consensus version 5.0.2, a logic error in Zebra's transaction verification cache could allow a malicious miner to induce a consensus split. By carefully submitting a transaction that is valid for height H+1 but invalid for H+2 and then mining that transaction in a block at height H+2, a miner could cause vulnerable Zebra nodes to accept an invalid block, leading to a consensus split from the rest of the Zcash network. This vulnerability is fixed in zebrad version 4.3.1 and zebra-consensus version 5.0.2.

Source published

21 Apr 2026 19:18:22 UTC

Source modified

21 Apr 2026 19:52:58 UTC

Observed here

23 Oct 2026 15:48:27 UTC

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CVSS 4.0 · 7.2 CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:N/VI:H/VA:H/SC:N/SI:H/SA:H