Low severity · published Oct 12, 2026
CVE-2026-109366
Zebra before 6.4.0 Gossiped Block Drop via Forged Coinbase scriptSig Height
3.7
CVSS
0.2%
EPSS
No
On KEV
Description
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.
CVSS vector
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:L
Attack vector
Network
Complexity
High
Privileges
None
User interaction
None
Confidentiality
None
Integrity
None
Availability
Low
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)0.2% · higher than 5% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
ZE
zebra · ZcashFoundation
before 6.4.0 · source: vendor
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-109366
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-109366
vendor-advisory
https://github.com/ZcashFoundation/zebra/security/advisories/GHSA-4f6v-mj46-gxg3
third-party-advisory
https://www.vulncheck.com/advisories/zebra-before-6.4.0-gossiped-block-drop-via-forged-coinbase-scriptsig-height
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