Vulnerability · Published Oct 2, 2026 · Assigned by VulnCheck
CVE-2026-104420Zebra before 6.3.0 Peer Misbehavior Ban Bypass via Gossiped Blocks
Medium 5.3
In plain English
A medium-severity security flaw in zebra from ZcashFoundation. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.3% (higher than 23% of all known vulnerabilities).
Severity (CVSS 3.1)5.3Medium
Exploit odds (30 days)0.3%top 76.7% of all CVEs
Exploited in the wildNo reportsCISA SSVC: none
Attack toolingNoneno public tooling known
Official 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 (as reported)
| Vendor | Product | Versions |
|---|---|---|
| ZcashFoundation | zebra | 0 – before 6.3.0 |
Weakness: CWE-704 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
References
- GitHub Security Advisory (GHSA-8hh2-hrf2-cqf4) vendor-advisory
- VulnCheck Advisory: Zebra before 6.3.0 Peer Misbehavior Ban Bypass via Gossiped Blocks third-party-advisory