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Medium · 5.3 CVE-2026-104420 EUVD-2026-91431GHSA-hfc4-gh7c-43q2

Zebra before 6.3.0 Peer Misbehavior Ban Bypass via Gossiped Blocks

Published Oct 2, 2026 · Updated Oct 6, 2026 · Assigned by VulnCheck

Description

Zebra before 6.3.0 contains a protection mechanism failure that allows unauthenticated peers to evade misbehavior scoring by supplying invalid gossiped blocks. The inbound cleanup step wrongly downcasts RouterError to VerifyBlockError and discards the score, so attackers can repeatedly force block download and Equihash verification without being banned.

Affected products

VendorProductAffectedFixed
ZcashFoundation zebra < 6.3.0 6.3.0

References