CVE-2026-40880

Description

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.

CVSS v3.1 Score

8.1

HIGH

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

EPSS — Exploit Prediction

0.0005

Probability of exploitation

0.14%

Percentile rank

EPSS estimates the probability that this vulnerability will be exploited in the wild within the next 30 days. A higher score means more likely to be exploited.

Weakness Type (CWE)

CWE-1025 CWE-1025

Affected Products

Vendor	Product	Versions
zfnd	zebra-consensus	< 5.0.2
zfnd	zebrad	< 4.3.1

References

Advisories & Patches

https://github.com/ZcashFoundation/zebra/security/advisories/GHSA-xvj8-ph7x-65gf

Frequently Asked Questions

What is CVE-2026-40880? +

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. It has a CVSS v3.1 base score of 8.1 (HIGH).

How severe is CVE-2026-40880? +

CVE-2026-40880 has a CVSS v3.1 score of 8.1 out of 10, rated HIGH. This is a high-severity vulnerability that should be prioritized for patching. The EPSS score is 0.0005, placing it in the 0th percentile for exploitation probability.

What products are affected by CVE-2026-40880? +

CVE-2026-40880 affects products from zfnd, specifically: zebra-consensus, zebrad. Check the affected products table above for specific version ranges.

How do I check if I'm vulnerable to CVE-2026-40880? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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