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High · 7.5 CVE-2026-104423 EUVD-2026-91434GHSA-4x5w-56x5-cmfr

Zebra before 6.2.1 Denial of Service via Uncapped V6 Shielded Proof Verification

Published Oct 2, 2026 · Updated Oct 2, 2026 · Assigned by VulnCheck

Description

Zebra (zebrad) before 6.2.1 contains an asymmetric resource consumption vulnerability that allows unauthenticated peers to stall block verification by pushing V6 mempool transactions with invalid Halo2 proofs. Attackers can flood the shared unprioritized Halo2 verification queue with zero-fee transactions carrying zero-filled Orchard and Ironwood proofs, causing nodes to fall behind the chain tip.

Affected products

VendorProductAffectedFixed
ZcashFoundation zebra < 6.2.1 6.2.1

References