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Zebra ConsensusApplication · Zfnd

CVE-2026-40880

HIGH · 8.1 CVSS v3.1 Published 2026-04-21
Fix available
A fix is available. Upgrade to 4.3.1 / 5.0.2 or later.
See remediation →
87/100
Remediation priority · High
Remotely reachable Zero-click

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
ZEBRA is a Zcash node written entirely in Rust. Prior to zebrad version 4.3.1 and zebra-consensus version 5.0.2, a logic error in Zebra's transaction verification cache could allow a malicious miner to induce a consensus split. By carefully submitting a transaction that is valid for height H+1 but invalid for H+2 and then mining that transaction in a block at height H+2, 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 vulnerability is fixed in zebrad version 4.3.1 and zebra-consensus version 5.0.2.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · high confidence

A logic error in Zebra's transaction verification cache allows a malicious miner to cause a consensus split by mining a transaction that is valid for height H+1 but invalid for height H+2, causing vulnerable Zebra nodes to incorrectly accept an invalid block at height H+2.

MitigationUpgrade zebrad to version 4.3.1 or zebra-consensus to version 5.0.2 or later to patch the transaction verification cache logic error.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
Zebra ConsensusApplication
Affected:< 5.0.2
ZebradApplication
Affected:< 4.3.1

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
Low
Privileges
Low
User interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
High
Availability
High

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:H

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Check zebrad version
    Run 'zebrad --version' or check the version flag available in your zebrad binary to determine the installed version
    Affected if The installed zebrad version is less than 4.3.1
  2. Check zebra-consensus version
    Run the zebra-consensus binary with a version flag or inspect the installed package version using your system's package manager
    Affected if The installed zebra-consensus version is less than 5.0.2
  3. Verify transaction verification cache is active
    Examine the zebra logs or configuration for transaction verification cache activity. This is typically enabled by default when zebra is running as a full node with transaction indexing
    Affected if Transaction verification cache is enabled (default behavior for vulnerable versions)

You are affected if your zebrad version is below 4.3.1 or your zebra-consensus version is below 5.0.2, and you are running with transaction verification enabled (the default full node configuration).

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Upgrade available Upgrade to 4.3.1 / 5.0.2 or later
Fixed in 4.3.15.0.2
Interim mitigation

Upgrade zebrad to version 4.3.1 or zebra-consensus to version 5.0.2 or later to patch the transaction verification cache logic error.

Recommended fix High confidence

zebrad >= 4.3.1 and zebra-consensus >= 5.0.2

  1. 1. Check the currently running versions of zebrad and zebra-consensus using `zebrad --version` or checking the running process
  2. 2. Stop the Zebra node service safely to prevent any disruption
  3. 3. Upgrade zebrad to version 4.3.1 or later and zebra-consensus to version 5.0.2 or later using the package manager or build from source
  4. 4. Restart the Zebra node service
  5. 5. Verify the upgraded versions are running correctly with `zebrad --version`
  6. 6. Monitor the node to ensure it is syncing correctly with the Zcash network and no consensus issues are occurring
Caveat Review the zebrad and zebra-consensus release notes between your current version and 4.3.1/5.0.2 for any breaking changes or migration requirements

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in Zebra Consensus Scoped from the published advisory
  • Consultation1.0 h
  • Implementation2.0 h
  • Testing3.0 h
  • Review / QA2.0 h
8.0 hours of engineering $1,370
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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2026-40880 in production — separate from our analysis above.

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
  • No weaponised exploit code, or anything meant to cause harm
  • No spam, self-promotion, credentials, or personal data