Consensus Divergence in Zebra 4.5.0 and Zebra-Script 7.0.0
CVE-2026-104430

8.7HIGH

Key Information:

Vendor

Zcashfoundation

Status
Zebra
Vendor
CVE Published:
2 October 2026

What is CVE-2026-104430?

The vulnerability in Zebra 4.5.0 and Zebra-Script 7.0.0 arises from the incorrect counting of P2SH redeem script signature operations. When operating in legacy mode, these products miscount signature operations, especially CHECKMULTISIG, leading to a significant overcount. This inconsistency creates a risky situation allowing remote attackers to broadcast P2SH spends utilizing low-threshold multisig redeem scripts. This action can result in creating blocks that zcashd will accept, but which exceed Zebra's inflated MAX_BLOCK_SIGOPS count. Consequently, Zebra nodes may reject these blocks, leading to potential stalling off the blockchain.

Affected Version(s)

zebra 4.5.0 < 4.5.1

zebra 7.0.0 < 7.0.1

zebra 4.5.1

References

https://github.com/ZcashFoundation/zebra/security/advisor...
vendor-advisory
https://www.vulncheck.com/advisories/zebra-4.5.0-consensu...
third-party-advisory

CVSS V4

Score:
8.7
Severity:
HIGH
Confidentiality:
None
Integrity:
None
Availability:
High
Attack Vector:
Network
Attack Complexity:
Low
Attack Required:
None
Privileges Required:
Undefined
User Interaction:
None

Timeline

  • Vulnerability published

  • Vulnerability Reserved

Credit

sangsoo-osec
.