Description
Zebra before 6.2.1 contains an incomplete cleanup vulnerability that allows unauthenticated peers to block downloading of valid blocks by leaving rejected hashes in SentHashes. Attackers can send a contextually invalid block sharing an honest block's header hash, causing Request::KnownBlock to skip the honest block and keep nodes behind the tip.
Published: 2026-10-02
Score: 6.9 Medium
EPSS: n/a
KEV: No
Impact: n/a
Action: n/a
AI Analysis

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Remediation

No vendor fix or workaround currently provided.

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Tracking

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Advisories

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History

Fri, 02 Oct 2026 14:00:00 +0000

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

Fri, 02 Oct 2026 13:30:00 +0000

Type Values Removed Values Added
Metrics ssvc

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


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

Type Values Removed Values Added
Description Zebra before 6.2.1 contains an incomplete cleanup vulnerability that allows unauthenticated peers to block downloading of valid blocks by leaving rejected hashes in SentHashes. Attackers can send a contextually invalid block sharing an honest block's header hash, causing Request::KnownBlock to skip the honest block and keep nodes behind the tip.
Title Zebra before 6.2.1 Block Download Denial of Service via KnownBlock SentHashes Lockout
First Time appeared Zfnd
Zfnd zebra
Weaknesses CWE-459
CPEs cpe:2.3:a:zfnd:zebra:*:*:*:*:*:*:*:*
Vendors & Products Zfnd
Zfnd zebra
References
Metrics cvssV3_1

{'score': 5.3, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L'}

cvssV4_0

{'score': 6.9, 'vector': 'CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N'}


cve-icon MITRE

Status: PUBLISHED

Assigner: VulnCheck

Published:

Updated: 2026-10-02T12:28:10.585Z

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

Link: CVE-2026-104421

cve-icon Vulnrichment

Updated: 2026-10-02T12:27:58.279Z

cve-icon NVD

Status : Received

Published: 2026-10-02T12:17:12.143

Modified: 2026-10-02T13:17:42.550

Link: CVE-2026-104421

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

Updated: 2026-10-02T13:45:17Z

Weaknesses