Vulnerability · Published Oct 12, 2026 · Assigned by VulnCheck

CVE-2026-109363Zebra 6.4.0 before 6.4.2 Denial of Service via Malformed v6 Transaction

High 7.5

In plain English

A high-severity security flaw in zebra from ZcashFoundation. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.4% (higher than 38% of all known vulnerabilities).

Severity (CVSS 3.1)7.5High

Exploit odds (30 days)0.4%top 62.4% of all CVEs

Exploited in the wildNo reportsCISA SSVC: none

Attack toolingNoneno public tooling known

Official 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.

Affected products (as reported)

Vendor	Product	Versions
ZcashFoundation	zebra	6.4.0 – before 6.4.2

Weakness: CWE-617 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

References

GitHub Security Advisory (GHSA-h5rr-8pqv-grp9) vendor-advisory
Patch Commit patch
VulnCheck Advisory: Zebra 6.4.0 before 6.4.2 Denial of Service via Malformed v6 Transaction third-party-advisory