What is CVE-2026-109363?

CVE-2026-109363 is a high-severity vulnerability in Zcashfoundation Zebra, classified under Reachable Assertion. CVSS score: 7.5/10. Published 2026-10-12.

How severe is CVE-2026-109363?

High severity. CVSS v3 base score is 7.5 out of 10.

Vulnerability in Zcashfoundation Zebra

CVE-2026-109363

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.

Published 2026-10-12.

CVSS v3 metric

CVSS v3 base score 7.5 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H.

EPSS exploit prediction

No EPSS score from FIRST.org yet. New CVEs usually get one within a few days; no score means no signal yet, not low risk. How EPSS works.

Affected products

Zcashfoundation Zebra

Weakness classification (CWE)

CWE-617 — Reachable Assertion

References

github.com/ZcashFoundation/zebra/security/advisories/GHSA-h5rr-8pqv-grp9 (vendor-advisory)
github.com/ZcashFoundation/zebra/commit/008abac5c99e872f283450d596d95e37851df49a (patch)
www.vulncheck.com/advisories/zebra-6.4.0-before-6.4.2-denial-of-service-via-mal… (third-party-advisory)

Frequently asked questions

What is CVE-2026-109363?: CVE-2026-109363 is a high-severity vulnerability in Zcashfoundation Zebra, classified under Reachable Assertion. CVSS score: 7.5/10. Published 2026-10-12.
How severe is CVE-2026-109363?: High severity. CVSS v3 base score is 7.5 out of 10.