CVE-2026-104430: Zcashfoundation Zebra

High severity, CVSS 7.5. EPSS: 0.4% chance of exploitation in the next 30 days.

Zebra zebrad 4.5.0 and zebra-script 7.0.0 count P2SH redeem script signature operations in legacy mode rather than zcashd's accurate P2SH mode, overcounting CHECKMULTISIG preceded by OP_1 through OP_16 as 20 sigops and causing a consensus divergence. Remote attackers can broadcast P2SH spends using low-threshold multisig redeem scripts so that a block zcashd accepts exceeds Zebra's inflated MAX_BLOCK_SIGOPS count, causing Zebra nodes to reject it and stall off the chain.

Affected products

• Zcashfoundation Zebra: from 4.5.0, before 4.5.1 (fixed in 4.5.1); from 7.0.0, before 7.0.1 (fixed in 7.0.1)

Published 2026-10-02. Last modified 2026-10-02.