CVE-2026-104420 PUBLISHED

Zebra before 6.3.0 Peer Misbehavior Ban Bypass via Gossiped Blocks

Assigner: VulnCheck
Reserved: 02.10.2026 Published: 02.10.2026 Updated: 02.10.2026

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.

CVSS Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N
CVSS Score: 6.9

Exploitability Metrics		Vulnerable System Impact Metrics		Subsequent System Impact Metrics
Attack Vector	Network	Confidentiality	None	Confidentiality	None
Attack Complexity	Low	Integrity	None	Integrity	None
Attack Requirements	None	Availability	Low	Availability	None
Privileges Required	None
User Interaction	None

CVSS 4.0

CVSS Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
CVSS Score: 5.3

Attack Vector	Network	Scope	Unchanged
Attack Complexity	Low	Confidentiality Impact	None
Privileges Required	None	Integrity Impact	None
User Interaction	None	Availability Impact	Low

CVSS 3.1

Product Status

Vendor	ZcashFoundation
Product	zebra
Versions	Default: unaffected affected from 0 to 6.3.0 (excl.) Version 6.3.0 is unaffected

CVE-2026-104420 PUBLISHED

Zebra before 6.3.0 Peer Misbehavior Ban Bypass via Gossiped Blocks

Metrics

Product Status

Credits

References

Problem Types