CVE-2026-104431: Zcashfoundation Zebra

High severity, CVSS 7.5. EPSS: 0.3% chance of exploitation in the next 30 days.

Zebra before 6.0.0 contains a denial of service vulnerability that allows unauthenticated peers to stall Tokio workers by submitting mempool transactions requiring expensive synchronous script verification. Attackers can send non-standard high-sigop P2SH transactions that reach CachedFfiTransaction::is_valid() before standardness checks, saturating the verifier buffer and rendering the node unresponsive.

Affected products

• Zcashfoundation Zebra: before 6.0.0 (fixed in 6.0.0)

Published 2026-10-02. Last modified 2026-10-02.