CVE-2026-104421Zebra before 6.2.1 Block Download Denial of Service via KnownBlock SentHashes Lockout
Updated under an hour ago ()
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It affects ZcashFoundation zebra. Add what you run to find out whether that includes you.
No exploitation reported and no EPSS estimate yet.
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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.
- CVSS
- 5.3 MEDIUM (v3.1, CNA)CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
- Weakness (CWE)
- CWE-459
- Known exploited
- Not in CISA's KEV catalog
- EPSS (exploitation in the next 30 days)
- Not loaded for this CVE
- Assigned by
- VulnCheck
- NVD analysis
- Deferred
- Record last updated
- Oct 2, 2026
- First seen by InfoSec Signals
- Oct 9, 2026
Affected products
ZcashFoundation zebra zcashfoundation:zebra (from the name) | before 6.2.1; 6.2.1 not affected | CNA record |
References
- https://github.com/ZcashFoundation/zebra/security/advisories/GHSA-x93j-mj2f-q338vendor-advisory
- https://www.vulncheck.com/advisories/zebra-before-6.2.1-block-download-denial-of-service-via-knownblock-senthashes-lockoutthird-party-advisory
The CVE record on cve.org NVD's entry
The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.