Zebra: Cached Mempool Verification Bypasses Consensus Rules for Ahead-of-Tip Blocks
Zebra: Cached Mempool Verification Bypasses Consensus Rules for Ahead-of-Tip Blocks. 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.
Vuln-watch · relayed from the GitHub Advisory Database; see Source & attribution below
Summary
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.
Affected
- zebra-consensus (rust) < 5.0.2 — fixed in 5.0.2
- zebrad (rust) < 4.3.1 — fixed in 4.3.1
Severity
High (CVSS 7.2), as rated by the upstream advisory.
Recommended actions
- Upgrade zebra-consensus to 5.0.2 or later
- Upgrade zebrad to 4.3.1 or later
Source & attribution
This 0xCERT advisory summarises GHSA-xvj8-ph7x-65gf / CVE-2026-40880 from the GitHub Advisory Database, credited upstream to sangsoo-osec, conradoplg, mpguerra: https://github.com/advisories/GHSA-xvj8-ph7x-65gf. Details may change; refer to the original source for the authoritative record.
References
OpenPGP-signed. The signed text of this advisory verifies against the 0xCERT key CCC7 D9EC 9415 723D.
Published 2026-04-18 · last updated 2026-10-08
curl -s https://www.0xcert.com/pgp.asc | gpg --import && curl -s https://www.0xcert.com/advisory/0xCERT-2026-0226/signed.txt | gpg --verify