CVE-2026-104421 — Zebra before 6.2.1 Block Download Denial of Service via KnownBlock SentHashes Lockout
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. …
Published: 2026-10-02 · CVSS: 6.9 · CVSS 4.0
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.
Source: CVE Program · Revision 8b16575c39f1e1810c5e863010da073d2d3285e7