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High severity · published Oct 12, 2026
CVE-2026-109363
Zebra 6.4.0 before 6.4.2 Denial of Service via Malformed v6 Transaction
7.5
CVSS
0.4%
EPSS
No
On KEV
Description
ZcashFoundation Zebra 6.4.0 before 6.4.2 parses version 6 transactions carrying a pre-NU6.3 consensus branch ID, but the size computation during UnminedTx construction treats re-serialization of the Orchard bundle as infallible, so the resulting error trips an expect that aborts zebrad. Unauthenticated peers can send a single pre-handshake tx message to crash the node, and can repeat this after each restart.
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Confidentiality
None
Integrity
None
Availability
High
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)0.4% · higher than 37% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
ZE
zebra · ZcashFoundation
6.4.0 before 6.4.2 · source: vendor
Affected product
ZE
zebra
ZcashFoundation
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-109363
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-109363
vendor-advisory
https://github.com/ZcashFoundation/zebra/security/advisories/GHSA-h5rr-8pqv-grp9
patch
https://github.com/ZcashFoundation/zebra/commit/008abac5c99e872f283450d596d95e37851df49a
third-party-advisory
https://www.vulncheck.com/advisories/zebra-6.4.0-before-6.4.2-denial-of-service-via-malformed-v6-transaction
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