CVE-2026-104422

High

Description

The block sync download path in Zebra (zebrad) before 6.3.0 reads a block's height from its unvalidated coinbase scriptSig and drops blocks that appear too far behind the tip before consensus validation, without penalizing the supplying peer. Because V5 transaction IDs exclude the scriptSig, a malicious peer can repeatedly serve a canonical block whose coinbase claims height 1 while keeping the requested hash, delaying the node's discovery of the newest block.

SeverityHigh

CVSS7.5

Exploit probability—

ProductZcashfoundation Zebra

PublishedOct 2, 2026

First seenOct 2, 2026

Weakness typeCWE-345CWE-345

How to fix

Update

ZcashFoundation zebra6.3.0 or later

Vendor advisories

github.com/ZcashFoundation/zebra/security/advisories/GHSA-g95h-hw6g-pvgv

Affected products

Product	Affected versions	Fixed in
ZcashFoundation zebra	v < 6.3.0	6.3.0

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