CVE-2026-109363

High

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.

SeverityHigh

CVSS7.5

Exploit probability—

ProductZcashfoundation Zebra

PublishedOct 12, 2026

First seenOct 12, 2026

Weakness typeCWE-617CWE-617

How to fix

Update

ZcashFoundation zebra6.4.2 or later

Patches

github.com/ZcashFoundation/zebra/commit/008abac5c99e872f283450d596d95e37851df49a

Vendor advisories

github.com/ZcashFoundation/zebra/security/advisories/GHSA-h5rr-8pqv-grp9

Affected products

Product	Affected versions	Fixed in
ZcashFoundation zebra	6.4.0 ≤ v < 6.4.2	6.4.2

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