Zebra has a Consensus Failure due to Improper Verification of V5 Transactions

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS 4.0

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 · score source

EPSS

• CVE-2026-34377: 0.26% estimated exploitation activity in the next 30 days; percentile 17.80 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

--- CVE-2026-34377: Consensus Failure via Crafted V5 Authorization Data Summary 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. To be clear, 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. Severity High - This is a Consensus Vulnerability that could allow a malicious miner to induce network partitioning, service disruption, and potential double-spend attacks against affected nodes. Affected Versions All Zebra versions supporting V5 transactions (Network Upgrade 5 and later) prior to version 4.3.0. Description The vulnerability exists in the findverifiedunminedtx function within…

Published by the source

30 Mar 2026, 19:13 UTC

Last modified by the source

9 Apr 2026, 15:06 UTC

Source last checked

26 Oct 2026, 15:42 UTC

1. Revision 1 · created · 26 Oct 2026

   Published from ghsa record GHSA-3vmh-33xr-9cqh

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# Patch Next advisory brief: CVE-2026-34377

Advisory: Zebra has a Consensus Failure due to Improper Verification of V5 Transactions
IDs: CVE-2026-34377, GHSA-3vmh-33xr-9cqh
Record: https://patchnext.com/advisories/cve-2026-34377 (revision 1, source checked 26 Oct 2026, 15:42 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: High (CVSS 8.4)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: zebra-consensus 5.0.1; zebrad 4.3.0. A vendor fix does not mean a deployment is fixed.

## Affected components
- crates.io zebra-consensus: affected < 5.0.1; fixed in 5.0.1
- crates.io zebrad: affected < 4.3.0; fixed in 4.3.0

## Suggested inspection (read-only)
- crates.io zebra-consensus: check the installed version with your package manager.
- crates.io zebrad: check the installed version with your package manager.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on zebra-consensus, zebrad.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://github.com/advisories/GHSA-3vmh-33xr-9cqh (GitHub-reviewed advisory GHSA-3vmh-33xr-9cqh lists affected ranges: crates.io zebrad >=0 =0 <5.0.1)

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