What’s Vulnerable › Vulnerabilities

CVE-2026-104430: Zebra 4.5.0 Consensus Split via P2SH Sigop Overcount

• Severity: high (CVSS 7.5 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.4% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-10-02 · updated 2026-10-02
• Weakness: CWE-628

Description

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; from 7.0.0 before 7.0.1 — fixed in 4.5.1, 7.0.1

How to fix

Upgrade to a fixed version: ZcashFoundation zebra 4.5.1, 7.0.1. Check the vendor advisory for mitigations.

References

• https://github.com/ZcashFoundation/zebra/security/advisories/GHSA-2prc-cj5x-4443
• https://www.vulncheck.com/advisories/zebra-4.5.0-consensus-split-via-p2sh-sigop-overcount

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