CVE-2026-104422
Zebra before 6.3.0 Block Sync Denial of Service via Coinbase scriptSig Rewrite
CVSS Score
7.5
EPSS Score
0.0%
EPSS Percentile
0th
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.
| CWE | CWE-345 |
| Vendor | zcashfoundation |
| Product | zebra |
| Published | Oct 2, 2026 |
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CVSS v3 Breakdown
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High
Affected Versions
ZcashFoundation / zebra
0 < 6.3.0
References
Credits
upbqdn