CVE-2026-104421CWE-459

CVE-2026-104421

Medium · published October 2, 2026

CVSS v3.1
5.3
EPSS
0%
Percentile
22.0
In the wild
Unconfirmed
What it is

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.

The record
Technical detail
CVSS v3.1
5.3 · MEDIUM
Vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
CVSS v4.0
6.9 · CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N
EPSS
0.00304 · 22.0th percentile
Weakness
CWE-459 · Incomplete Cleanup
Published
2026-10-02T16:17Z
References (2)
https://github.com/ZcashFoundation/zebra/security/advisories/GHSA-x93j-mj2f-q338 · [email protected]https://www.vulncheck.com/advisories/zebra-before-6.2.1-block-download-denial-of-service-via-knownblock-senthashes-lockout · [email protected]
EPSS history
Timeline
  • 04 OCT 03:27Z
    EPSS moved — → 0%
    epss
  • 02 OCT 11:38Z
    Zebra before 6.2.1 Block Download Denial of Service via KnownBlock SentHashes Lockout
    cvelistv5