CVE-2026-123556 Details
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.
A vulnerability exists in Zcash Foundation's Zebra version 4.5.0 prior to 7.0.0, where the mempool lock-time rejection is improperly scored, causing honest peers to be banned. This issue allows attackers to send transactions locked until the current block height right after each block is mined, leading to bans on honest relaying peers for 24 hours or until they restart. The problem arises because lagging nodes reject these transactions due to lock-time errors, while nodes that are up to date accept them as valid.
Upgrade to Zcash Foundation Zebra version 7.0.0 or later, where this vulnerability has been fixed. If an upgrade is not possible, keeping the node well-connected and in sync can help reduce the frequency of being one block behind relaying peers.
Metrics
CVSS 4.0 Severity and Vector Strings:
VolerionCVSS 3.x Severity and Vector Strings:
No data available for CVSS Version 2.0 on this CVE.
Volerion
Assessed Nov 8, 2026References to Advisories, Solutions, and Tools
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Weakness Enumeration
| CWE-ID | CWE Name | Source |
|---|---|---|
| CWE-693 | Protection Mechanism Failure | [email protected] |
Affected Products
| Product | Versions |
|---|---|
| ZcashFoundation Zebra | >= 4.5.0, < 7.0.0 (semver) 7.0.0-rc.0 (semver) |
CPE
Remediation
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Change History
1 change record found show changes
| Date | Action | Recorded By |
|---|---|---|
| Nov 8, 2026 | New CVE Received | [email protected] |