Is CVE-2026-104430 exploited in the wild?

No. Junglewise Threat Intelligence has no report of CVE-2026-104430 being exploited in the wild.

How severe is CVE-2026-104430?

High severity, with a CVSS score of 7.5, published 2 October 2026.

Which products and versions are affected?

Zcash Foundation Zebra-Script 7.0.0; Zcash Foundation Zebrad 4.5.0.

How is CVE-2026-104430 attacked?

It is attacked over the network, in a hosted service.

Am I affected by CVE-2026-104430?

Check whether you run Zcash Foundation Zebra-Script or Zcash Foundation Zebrad at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

CVE-2026-104430: Zebra P2SH sigop counting consensus divergence

CVE-2026-104430 · Severity: high · CVSS 7.5 · Published 2026-10-02

Zebra is a Zcash node implementation that validates blocks on the Zcash blockchain. Versions 4.5.0 and 7.0.0 incorrectly count signature operations in payment script hashes (P2SH), causing them to reject valid blocks that other nodes accept. An attacker can broadcast transactions with low-threshold multisig scripts that trigger this miscounting, splitting Zebra nodes away from the rest of the network and halting their operation.

Technologies: Zcash Foundation Zebra-Script, Zcash Foundation Zebrad. Vendors: Zcash Foundation.

Quick answers

Is CVE-2026-104430 exploited in the wild?: No. Junglewise Threat Intelligence has no report of CVE-2026-104430 being exploited in the wild.
How severe is CVE-2026-104430?: High severity, with a CVSS score of 7.5, published 2 October 2026.
Which products and versions are affected?: Zcash Foundation Zebra-Script 7.0.0; Zcash Foundation Zebrad 4.5.0.
Is there a fix for CVE-2026-104430?: Yes: fixed in zebrad 4.5.1, zebra-script 7.0.1. Until then: No configuration-level workaround exists; all Zebra nodes validating blocks on networks shared with zcashd nodes are affected and must upgrade. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
How is CVE-2026-104430 attacked?: It is attacked over the network, in a hosted service.
Am I affected by CVE-2026-104430?: Check whether you run Zcash Foundation Zebra-Script or Zcash Foundation Zebrad at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

How to fix

Fixed in: zebrad 4.5.1, zebra-script 7.0.1

No configuration-level workaround exists; all Zebra nodes validating blocks on networks shared with zcashd nodes are affected and must upgrade.

Technical details

The vulnerability is a function call with incorrectly specified arguments (CWE-628): Zebra calls the legacy P2SH sigop counter with the wrong mode flag, counting CHECKMULTISIG operations as 20 instead of the actual 1–16 key count. This causes blocks with ~1,000+ low-threshold multisig P2SH inputs to exceed Zebra's MAX_BLOCK_SIGOPS threshold of 20,000 while remaining valid on zcashd nodes, resulting in a consensus split. No special privileges, mining capability, or user interaction is required; broadcasting ordinary P2SH transactions is sufficient.

Affected products

Zcash Foundation zebrad 4.5.0
Zcash Foundation zebra-script 7.0.0

Timeline

2026-06-01: disclosed: GitHub Security Advisory GHSA-2prc-cj5x-4443 published
2026-10-02: advisory: CVE-2026-104430 published

References

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