CVE-2026-109363 Zebra 6.4.0 before 6.4.2 Denial of Service via Malformed v6 Transaction
Unauthenticated attackers can crash the Zebra node by sending a malformed transaction, causing a denial of service.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2026-109363?
CVE-2026-109363 is a high-severity denial of service vulnerability in ZcashFoundation zebra, published on 12 Oct 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
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.
Weakness: CWE-617
Which versions are affected by CVE-2026-109363?
How do I fix CVE-2026-109363?
No fix has been published for CVE-2026-109363 yet. Limit exposure of the affected software until one is available.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
Is CVE-2026-109363 being exploited?
There is no known exploitation of CVE-2026-109363 in the wild and no public exploit code.
Sources
Also known as GHSA-47j7-v7c6-f9jg, GHSA-h5rr-8pqv-grp9.