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.

Attack Vector Network

Attack Complexity Low

Privileges Required None

Attack Requirements None

User Interaction None

Vulnerable System Confidentiality Impact None

Vulnerable System Integrity Impact None

Vulnerable System Availability Impact High

Subsequent System Confidentiality Impact None

Subsequent System Integrity Impact None

Subsequent System Availability Impact None

Attack Vector Network

Attack Complexity Low

Privileges Required None

Scope Unchanged

Confidentiality Impact None

Integrity Impact None

Availability Impact High

User Interaction None

No CVSS v3.0

No CVSS v2

This CVE is not in the KEV list.

No EPSS score available.

Key SSVC decision points have not yet been added.

Default status is the baseline for the product, each version can override it (e.g. patched versions marked unaffected).

Vendor Product Default status Versions
ZcashFoundation zebra unaffected
Version Status Constraints
0 affected < 6.3.0
6.3.0 unaffected —

No data.

No data.

OpenCVE Enrichment is a feature of OpenCVE that uses AI to automatically link vendors and products to CVEs. Learn more on GitHub.

No data.

Project Subscriptions

Vendors Products
Zfnd Subscribe
Zebra Subscribe
Advisories

No advisories yet.

Fixes

Solution

No solution given by the vendor.

Workaround

No workaround given by the vendor.

References
Link Providers
https://github.com/ZcashFoundation/zebra/security/advisories/GHSA-g95h-hw6g-pvgv cve-icon cve-icon
https://www.vulncheck.com/advisories/zebra-before-6.3.0-block-sync-denial-of-service-via-coinbase-scriptsig-rewrite cve-icon cve-icon
History

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'}

Projects

Sign in to view the affected projects.

cve-icon MITRE

Status: PUBLISHED

Assigner: VulnCheck

Published:

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

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

Link: CVE-2026-104422

cve-icon Vulnrichment

No data.

cve-icon NVD

Status : Received

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

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

Link: CVE-2026-104422

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

Updated: 2026-10-02T12:30:20Z

Weaknesses