Medium severity5.3NVD Advisory· Published Oct 2, 2026· Updated Oct 2, 2026

CVE-2026-104421

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.

Affected products

ZcashFoundation/Zebrallm-fuzzy
Range: <6.2.1

Patches

Vulnerability mechanics

References

github.com/ZcashFoundation/zebra/security/advisories/GHSA-x93j-mj2f-q338nvd
www.vulncheck.com/advisories/zebra-before-6.2.1-block-download-denial-of-service-via-knownblock-senthashes-lockoutnvd

News mentions

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cvss	0.345
epss	0.000
exploit	0.000
kev	0.000
patch	-0.070
ransomware	0.000