CVE-2026-123556
Deferred Deferred - Pending Action

Zebra Protection Mechanism Failure Allows Honest Peer Banning

Publication date: 2026-11-08

Last updated on: 2026-11-08

Assigner: VulnCheck

Description
ZcashFoundation Zebra from 4.5.0 before 7.0.0 contains a protection mechanism failure that bans honest peers by scoring mempool lock-time rejections at the ban threshold. Attackers can broadcast transactions locked until the current height right after each block, causing lagging nodes to ban honest relaying peers for 24 hours or until restart.

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Meta Information

Published
2026-11-08
Last Modified
2026-11-08
Generated
2026-11-08
AI Q&A
2026-11-08
EPSS Evaluated
N/A
NVD
CVE-2026-123556
EUVD
EUVD-2026-119441

Affected Vendors & Products

Showing 1 associated CPE
Vendor Product Version / Range
zcashfoundation zebra From 4.5.0 (inc) to 7.0.0 (exc)

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Exploitability

CWE
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KEV
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CWE ID Description
CWE-693 The product does not use or incorrectly uses a protection mechanism that provides sufficient defense against directed attacks against the product.

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Executive Summary

ZcashFoundation Zebra versions 4.5.0 to 7.0.0 have a flaw where honest peers are incorrectly banned due to scoring mempool lock-time rejections at the ban threshold. Attackers exploit this by broadcasting transactions locked to the current block height, causing lagging nodes to ban honest relaying peers for 24 hours or until a restart.

Impact Analysis

This vulnerability can disrupt network operations by causing honest peers to be banned, leading to reduced peer connectivity and potential delays in transaction processing. Users running affected Zebra versions may experience network instability or temporary exclusion from the network.

Mitigation Strategies

Upgrade Zebra to version 7.0.0 or later to address the protection mechanism failure. Restart affected nodes to clear temporary bans. Monitor peer connections for unusual bans or rejections.

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