What’s Vulnerable › Vulnerabilities

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

• Severity: high (CVSS 7.5 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.4% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-10-12 · updated 2026-10-15
• Weakness: CWE-617

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

• ZcashFoundation zebra: from 6.4.0 before 6.4.2 — fixed in 6.4.2

How to fix

Upgrade to a fixed version: ZcashFoundation zebra 6.4.2. Check the vendor advisory for mitigations.

References

• https://github.com/ZcashFoundation/zebra/commit/008abac5c99e872f283450d596d95e37851df49a
• https://github.com/ZcashFoundation/zebra/security/advisories/GHSA-h5rr-8pqv-grp9
• https://www.vulncheck.com/advisories/zebra-6.4.0-before-6.4.2-denial-of-service-via-malformed-v6-transaction

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