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.
History

Sat, 03 Oct 2026 06:30:00 +0000

Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'yes', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}


Fri, 02 Oct 2026 16:00:00 +0000

Type Values Removed Values Added
First Time appeared Zcashfoundation
Zcashfoundation zebra
Vendors & Products Zcashfoundation
Zcashfoundation zebra

Fri, 02 Oct 2026 11:45:00 +0000

Type Values Removed Values Added
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.
Title Zebra before 6.3.0 Block Sync Denial of Service via Coinbase scriptSig Rewrite
First Time appeared Zfnd
Zfnd zebra
Weaknesses CWE-345
CPEs cpe:2.3:a:zfnd:zebra:*:*:*:*:*:*:*:*
Vendors & Products Zfnd
Zfnd zebra
References
Metrics cvssV3_1

{'score': 7.5, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H'}

cvssV4_0

{'score': 8.7, 'vector': 'CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N'}


cve-icon MITRE

Status: PUBLISHED

Assigner: VulnCheck

Published: 2026-10-02T11:38:03.646Z

Updated: 2026-10-02T17:35:03.530Z

Reserved: 2026-10-02T00:46:23.830Z

Link: CVE-2026-104422

cve-icon Vulnrichment

Updated: 2026-10-02T17:34:58.961Z

cve-icon NVD

Status : Deferred

Published: 2026-10-02T12:17:12.283

Modified: 2026-10-02T18:17:01.303

Link: CVE-2026-104422

cve-icon Redhat

No data.