{
  "affected": [
    {
      "ranges": [
        {
          "database_specific": {
            "extracted_events": [
              {
                "introduced": "0"
              },
              {
                "fixed": "6.2.1"
              }
            ],
            "source": [
              "AFFECTED_FIELD",
              "DESCRIPTION"
            ]
          },
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "f3edc40601b4a377693a32c982d4cddf1795fb6f"
            }
          ],
          "repo": "https://github.com/zcashfoundation/zebra",
          "type": "GIT"
        }
      ]
    }
  ],
  "aliases": [
    "GHSA-x93j-mj2f-q338"
  ],
  "database_specific": {
    "cna_assigner": "VulnCheck",
    "cwe_ids": [
      "CWE-459"
    ],
    "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/104xxx/CVE-2026-104421.json"
  },
  "details": "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.",
  "id": "CVE-2026-104421",
  "modified": "2026-10-04T02:30:17.957643377Z",
  "published": "2026-10-02T11:38:02.456Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/104xxx/CVE-2026-104421.json"
    },
    {
      "type": "ADVISORY",
      "url": "https://github.com/ZcashFoundation/zebra/security/advisories/GHSA-x93j-mj2f-q338"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-104421"
    },
    {
      "type": "ADVISORY",
      "url": "https://www.vulncheck.com/advisories/zebra-before-6.2.1-block-download-denial-of-service-via-knownblock-senthashes-lockout"
    }
  ],
  "schema_version": "1.9.0",
  "severity": [
    {
      "score": "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",
      "type": "CVSS_V4"
    }
  ],
  "summary": "Zebra before 6.2.1 Block Download Denial of Service via KnownBlock SentHashes Lockout"
}