CVE-2026-104421
Medium
Description
Zebra before 6.2.1 contains an incomplete cleanup vulnerability that allows unauthenticated peers to block downloading of valid blocks by leaving rejected hashes in SentHashes. Attackers can send a contextually invalid block sharing an honest block's header hash, causing Request::KnownBlock to skip the honest block and keep nodes behind the tip.
SeverityMedium
CVSS5.3
Exploit probability23. percentile0.3%
ProductZcashfoundation Zebra
PublishedOct 2, 2026
First seenOct 2, 2026
Weakness typeCWE-459CWE-459
How to fix
Update
- ZcashFoundation zebra6.2.1 or later
Affected products
| Product | Affected versions | Fixed in |
|---|---|---|
| ZcashFoundation zebra | v < 6.2.1 | 6.2.1 |
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