Is CVE-2026-104420 being exploited?

No public exploit is currently tracked.

How severe is CVE-2026-104420?

CVE-2026-104420 has a CVSS v3 severity of MEDIUM (5.3).

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CVE-2026-104420

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.