# CVE-2026-40880: Zebra: Cached Mempool Verification Bypasses Consensus Rules for Ahead-of-Tip Blocks

Source: https://junglewise.ai/threats/cve-2026-40880-zebra-cached-mempool-verification-bypasses-consensus-rules-for  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-04-21. Updated: 2026-05-11  
License: CC BY 4.0 with a link back

CVE-2026-40880 · Severity: high · CVSS 8.1 · Published 2026-04-21

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.

Technologies: [zebra-consensus (crates.io)](https://junglewise.ai/threats/technologies/zebra-consensus), [zebrad (crates.io)](https://junglewise.ai/threats/technologies/zebrad), [Zfnd Zebrad](https://junglewise.ai/threats/technologies/zfnd-zebrad). Vendors: [crates.io](https://junglewise.ai/threats/vendors/crates-io), [Zfnd](https://junglewise.ai/threats/vendors/zfnd).

## Quick answers

**Is CVE-2026-40880 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-40880 being exploited in the wild.

**How severe is CVE-2026-40880?** High severity, with a CVSS score of 8.1, published 21 April 2026.

**Which products and versions are affected?** zebra-consensus (crates.io) < 5.0.2, SEMVER:introduced=0,fixed=5.0.2; zebrad (crates.io) < 4.3.1, SEMVER:introduced=0,fixed=4.3.1.

**Is there a fix for CVE-2026-40880?** Yes. zebra-consensus (crates.io): upgrade to 5.0.2 or later; zebrad (crates.io): upgrade to 4.3.1 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**Am I affected by CVE-2026-40880?** Check whether you run zebra-consensus (crates.io), zebrad (crates.io), Zfnd Zebra-Consensus or one of the others listed at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## How to fix

- zebra-consensus (crates.io): upgrade to 5.0.2 or later

  ```sh
  cargo update -p zebra-consensus
  ```

- zebrad (crates.io): upgrade to 4.3.1 or later

  ```sh
  cargo update -p zebrad
  ```


## Affected products

- zebra-consensus (crates.io) < 5.0.2, SEMVER:introduced=0,fixed=5.0.2
- zebrad (crates.io) < 4.3.1, SEMVER:introduced=0,fixed=4.3.1
- Zfnd Zebra-Consensus
- Zfnd Zebrad

## Identifiers

- CVE-2026-40880
- GHSA-xvj8-ph7x-65gf

## References

- [https://api.github.com/users/sangsoo-osec](https://api.github.com/users/sangsoo-osec)
- [https://github.com/sangsoo-osec](https://github.com/sangsoo-osec)
- [https://api.github.com/users/sangsoo-osec/gists%7B/gist_id%7D](https://api.github.com/users/sangsoo-osec/gists%7B/gist_id%7D)
- [https://api.github.com/users/sangsoo-osec/repos](https://api.github.com/users/sangsoo-osec/repos)
- [https://avatars.githubusercontent.com/u/129559837?v=4](https://avatars.githubusercontent.com/u/129559837?v=4)
- [https://api.github.com/users/sangsoo-osec/events%7B/privacy%7D](https://api.github.com/users/sangsoo-osec/events%7B/privacy%7D)

## Related threats

- [ZcashFoundation Zebra assertion panic in address book mempool update](https://junglewise.ai/threats/cve-2026-52829-zcashfoundation-zebra-assertion-panic-in-address-book-mempool)
- [ZcashFoundation Zebra process abort via repeated shielded transactions](https://junglewise.ai/threats/cve-2026-52739-zcashfoundation-zebra-process-abort-via-repeated-shielded)
- [ZcashFoundation Zebra denial of service via balance overflow in state writer](https://junglewise.ai/threats/cve-2026-52738-zcashfoundation-zebra-denial-of-service-via-balance-overflow-in)
- [Zcash Zebra sync restart poisoning via above-lookahead block](https://junglewise.ai/threats/cve-2026-52737-zcash-zebra-sync-restart-poisoning-via-above-lookahead-block)
- [ZcashFoundation Zebra block suppression via same-header body poisoning](https://junglewise.ai/threats/cve-2026-52736-zcashfoundation-zebra-block-suppression-via-same-header-body)