{
  "affected": [
    {
      "ranges": [
        {
          "database_specific": {
            "extracted_events": [
              {
                "range": [
                  {
                    "introduced": "0"
                  },
                  {
                    "fixed": "4.86.2"
                  }
                ],
                "source": "AFFECTED_FIELD",
                "strategy": "StandardRange"
              }
            ]
          },
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "4e5054a373e25a600d2c668e7fea3e48960f31e7"
            }
          ],
          "repo": "https://github.com/fleetdm/fleet",
          "type": "GIT"
        }
      ]
    }
  ],
  "aliases": [
    "GHSA-mjrh-3v6h-8g5p"
  ],
  "database_specific": {
    "cna_assigner": "VulnCheck",
    "cwe_ids": [
      "CWE-407"
    ],
    "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/126xxx/CVE-2026-126401.json"
  },
  "details": "Fleet before 4.86.2 contains a denial of service vulnerability that allows unauthenticated attackers to exhaust server memory through quadratic XML canonicalization of unsigned SAML responses. Attackers can send a single crafted SAML response with deeply nested elements declaring new namespace prefixes to POST /api/v1/fleet/sso/callback, crashing the Fleet server.",
  "id": "CVE-2026-126401",
  "modified": "2026-11-14T02:30:47.118188409Z",
  "published": "2026-11-13T09:35:47.679Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/126xxx/CVE-2026-126401.json"
    },
    {
      "type": "ADVISORY",
      "url": "https://github.com/fleetdm/fleet/security/advisories/GHSA-mjrh-3v6h-8g5p"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-126401"
    },
    {
      "type": "ADVISORY",
      "url": "https://www.vulncheck.com/advisories/fleet-before-4.86.2-unauthenticated-dos-via-sso-callback-xml-canonicalization"
    }
  ],
  "schema_version": "1.9.2",
  "severity": [
    {
      "score": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N",
      "type": "CVSS_V4"
    }
  ],
  "summary": "Fleet before 4.86.2 Unauthenticated DoS via SSO Callback XML Canonicalization"
}