# CVE-2026-34377: Zebra has a Consensus Failure due to Improper Verification of V5 Transactions

> A malicious miner can cause a consensus split in Zebra nodes by exploiting a transaction verification cache logic error, disrupting network agreement.

- **Severity:** High 8.4 (`CVSS:4.0/AV:N/AC:L/AT:N/PR:H/UI:N/VC:N/VI:H/VA:H/SC:N/SI:H/SA:H`)
- **Exploited in the wild:** Not known
- **Login needed:** An administrator
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 31 Mar 2026
- **Updated:** 31 Mar 2026
- **Also known as:** GHSA-3vmh-33xr-9cqh

## What is CVE-2026-34377?

CVE-2026-34377 is a high-severity vulnerability in ZcashFoundation zebra, published on 31 Mar 2026. An attacker needs administrator access to exploit it, with no action from the victim.

### Official description

ZEBRA is a Zcash node written entirely in Rust. Prior to zebrad version 4.3.0 and zebra-consensus version 5.0.1, a logic error in Zebra's transaction verification cache could allow a malicious miner to induce a consensus split. By matching a valid transaction's txid while providing invalid authorization data, a miner could cause vulnerable Zebra nodes to accept an invalid block, leading to a consensus split from the rest of the Zcash network. This would not allow invalid transactions to be accepted but could result in a consensus split between vulnerable Zebra nodes and invulnerable Zebra and Zcashd nodes. This issue has been patched in zebrad version 4.3.0 and zebra-consensus version 5.0.1.

Weakness: CWE-347 (Improper Verification of Cryptographic Signature)

## Which versions are affected by CVE-2026-34377?

4 open source packages ship an affected version, including zebra-consensus and zebrad. It affects 2 products.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `zebra-consensus` | crates.io | All versions | 5.0.1 |
| `zebra-consensus` | crates.io | All versions | 5.0.1 |
| `zebrad` | crates.io | All versions | 4.3.0 |
| `zebrad` | crates.io | All versions | 4.3.0 |

Products: Zfnd Zebra, Zfnd Zebra-Consensus.

## How do I fix CVE-2026-34377?

Upgrade zebra-consensus to 5.0.1 or later.

## Is CVE-2026-34377 being exploited?

There is no known exploitation of CVE-2026-34377 in the wild and no public exploit code.

## Other vulnerabilities in ZcashFoundation zebra

- [CVE-2026-34202](https://insights.sbomify.com/CVE-2026-34202/): Zebra node crash — V5 transaction hash panic (P2P reachable) (critical 9.2)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-34377 and fix it if it is affected.

What it is: CVE-2026-34377 is a high-severity vulnerability in ZcashFoundation zebra, published on 31 Mar 2026. An attacker needs administrator access to exploit it, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-34377 in the wild and no public exploit code.

Affected packages and fixed versions:
- zebra-consensus (crates.io): affected all versions; fixed in 5.0.1
- zebra-consensus (crates.io): affected all versions; fixed in 5.0.1
- zebrad (crates.io): affected all versions; fixed in 4.3.0
- zebrad (crates.io): affected all versions; fixed in 4.3.0

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-2026-34377/ (Markdown: https://insights.sbomify.com/CVE-2026-34377/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-34377
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-34377
- OSV: https://osv.dev/vulnerability/CVE-2026-34377

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-34377/
Summaries are generated and may contain mistakes; the official description above is the record.