CVE-2026-104422: Zcashfoundation Zebra

High severity, CVSS 7.5. EPSS: 0.2% chance of exploitation in the next 30 days.

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.

Affected products

• Zcashfoundation Zebra: before 6.3.0 (fixed in 6.3.0)

Published 2026-10-02. Last modified 2026-10-02.