CVE-2026-109366

LOW 3.7

Zebra before 6.4.0 Gossiped Block Drop via Forged Coinbase scriptSig Height

CVSS Score

3.7

EPSS Score

0.0%

EPSS Percentile

0th

Zebra before 6.4.0 contains an improper integrity validation vulnerability in the inbound gossip download path that allows unauthenticated peers to force dropping of new blocks without penalty. Attackers can serve a real block with a coinbase scriptSig rewritten to height 1, which keeps the ZIP-244 block hash, triggering a behind-tip drop before consensus validation and delaying tip discovery for mining backends.

CWE	CWE-354
Vendor	zcashfoundation
Product	zebra
Published	Oct 12, 2026

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CVSS v3 Breakdown

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:L

Attack Vector

Network

Attack Complexity

High

Privileges Required

None

User Interaction

None

Scope

Unchanged

Confidentiality

None

Integrity

None

Availability

Low

Affected Versions

ZcashFoundation / zebra

0 < 6.4.0

References

NVD ↗ CVE.org ↗ EPSS Data ↗

github.com: https://github.com/ZcashFoundation/zebra/security/advisories/GHSA-4f6v-mj46-gxg3 vulncheck.com: https://www.vulncheck.com/advisories/zebra-before-6.4.0-gossiped-block-drop-via-forged-coinbase-scriptsig-height

Credits

🔍 craftsoldier arya2 conradoplg mpguerra