CVE-2026-40880 HIGH

CVE-2026-40880: Zebra: Cached Mempool Verification Bypasses Consensus Rules for Ahead-of-Tip Blocks

Vendor Zcashfoundation
Product zebrad
Weakness CWE-1025
Published April 21, 2026
Last update April 21, 2026

CVSS base score

7.2/10
Attack vector Network
Attack complexity Low
Privileges required Low
User interaction None
Confidentiality
Integrity

CVSS vector

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

What the vulnerability does

01Description

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.

Key dates

02Disclosure timeline

April 21, 2026 CVE published
April 21, 2026 Record updated