CVE-2026-40880
Published: 21 April 2026
Summary
CVE-2026-40880 is a high-severity Comparison Using Wrong Factors (CWE-1025) vulnerability in Zfnd Zebra-Consensus. Its CVSS base score is 8.1 (High).
Operationally, exploitation aligns with the MITRE ATT&CK technique Exploit Public-Facing Application (T1190); ranked at the 14.4th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog.
The strongest mitigations our analysis identified are NIST 800-53 RA-5 (Vulnerability Monitoring and Scanning) and SI-2 (Flaw Remediation).
Threat & Defense at a Glance
Threat & Defense Details
Mitigating Controls (NIST 800-53 r5)AI
Timely flaw remediation by upgrading to zebrad 4.3.1 and zebra-consensus 5.0.2 directly eliminates the transaction verification cache logic error that enables consensus splits.
Vulnerability monitoring and scanning identifies vulnerable Zebra versions affected by CVE-2026-40880, enabling proactive patching before malicious miner exploitation.
Verification of transaction verification security functions ensures the cache logic correctly handles transactions invalid at specific block heights, mitigating acceptance of invalid blocks.
MITRE ATT&CK Enterprise TechniquesAI
Why these techniques?
The CVE describes a logic error in the public-facing Zcash node (Zebra) that is directly exploitable over the network by a low-privileged attacker to cause nodes to accept invalid blocks and trigger a consensus split, mapping to exploitation of a public-facing application.
NVD 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…
more
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.
Deeper analysisAI
CVE-2026-40880 is a logic error in the transaction verification cache of Zebra, a Zcash node written entirely in Rust. The vulnerability affects zebrad versions prior to 4.3.1 and zebra-consensus versions prior to 5.0.2, enabling a consensus split under specific conditions. It has a CVSS v3.1 base score of 8.1 (AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:H) and is associated with CWE-1025.
A malicious miner with low privileges can exploit this vulnerability over the network with low complexity and no user interaction. By submitting a transaction valid for block height H+1 but invalid for H+2, and then mining that transaction into a block at height H+2, the attacker causes vulnerable Zebra nodes to accept the invalid block. This leads to a consensus split, where affected nodes diverge from the rest of the Zcash network, compromising integrity and availability.
The vulnerability is fixed in zebrad version 4.3.1 and zebra-consensus version 5.0.2. Additional details on the issue and mitigation are available in the GitHub Security Advisory at https://github.com/ZcashFoundation/zebra/security/advisories/GHSA-xvj8-ph7x-65gf.
Details
- CWE(s)