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

> Remote attackers can cause Zebra nodes to stall off the chain by broadcasting blocks that trigger a consensus divergence due to incorrect signature operation counting.

- **Severity:** High 8.7 (`CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 2 Oct 2026
- **Updated:** 2 Oct 2026
- **Also known as:** GHSA-2prc-cj5x-4443, GHSA-4c53-mmm8-cf87

## What is CVE-2026-104430?

CVE-2026-104430 is a high-severity denial of service vulnerability in ZcashFoundation zebra, published on 2 Oct 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official 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.

Weakness: CWE-628 (Function Call with Incorrectly Specified Arguments)

## Which versions are affected by CVE-2026-104430?


## How do I fix CVE-2026-104430?

No fix has been published for CVE-2026-104430 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-104430 being exploited?

There is no known exploitation of CVE-2026-104430 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-104430 and fix it if it is affected.

What it is: CVE-2026-104430 is a high-severity denial of service vulnerability in ZcashFoundation zebra, published on 2 Oct 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-104430 in the wild and no public exploit code.

Affected product: ZcashFoundation zebra. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-104430/ (Markdown: https://insights.sbomify.com/CVE-2026-104430/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-104430
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-104430
- OSV: https://osv.dev/vulnerability/CVE-2026-104430

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-104430/
Summaries are generated and may contain mistakes; the official description above is the record.