Security advisory

{
  "id": "9a42eca72ae92bd0751ca00b0e4b9b7137a782305a4261b6c9e55d31ed95049d",
  "url": "https://osv.dev/vulnerability/CVE-2020-26276",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "CVE-2020-26276",
    "summary": "Fleet is an open source osquery manager. In Fleet before version 3.5.1, due to issues in Go's standard library XML parsing, a valid SAML response may be mutated by an attacker to modify the trusted document. This can result in allowing unverified logins from a SAML IdP. Users that configure Fleet with SSO login may be vulnerable to this issue. This issue is patched in 3.5.1. The fix was made using https://github.com/mattermost/xml-roundtrip-validator If upgrade to 3.5.1 is not possible, users should disable SSO authentication in Fleet.",
    "evidence": "osv:CVE-2020-26276",
    "products": [],
    "severity": "critical",
    "structured": {
      "id": "CVE-2020-26276",
      "aliases": [
        "CVE-2020-26276",
        "GHSA-w3wf-cfx3-6gcx"
      ],
      "metrics": [
        {
          "type": "CVSS_V3",
          "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "repo": "https://github.com/fleetdm/fleet",
              "type": "GIT",
              "events": [
                {
                  "introduced": "0"
                },
                {
                  "fixed": "55a2aa2c955a99483b730e60207e4afada7bda8a"
                },
                {
                  "fixed": "57812a532e5f749c8e18c6f6a652eca65c083607"
                }
              ],
              "database_specific": {
                "extracted_events": [
                  {
                    "cpe": "cpe:2.3:a:fleetdm:fleet:*:*:*:*:*:*:*:*",
                    "range": [
                      {
                        "introduced": "0"
                      },
                      {
                        "fixed": "3.5.1"
                      }
                    ],
                    "source": "CPE_RANGE"
                  },
                  {
                    "range": [
                      {
                        "fixed": "57812a532e5f749c8e18c6f6a652eca65c083607"
                      }
                    ],
                    "source": "REFERENCES_COMMIT"
                  }
                ]
              }
            }
          ],
          "versions": [
            "3.5.0",
            "3.4.0",
            "3.3.0",
            "3.2.0",
            "3.1.0",
            "3.0.0",
            "2.6.0",
            "2.5.0",
            "2.4.0",
            "2.3.0",
            "2.2.0",
            "2.1.2",
            "2.1.1",
            "2.1.0",
            "2.0.2",
            "2.0.1",
            "2.0.0",
            "2.0.0-rc5",
            "2.0.0-rc4",
            "2.0.0-rc3",
            "2.0.0-rc2",
            "2.0.0-rc1",
            "1.0.7",
            "1.0.6",
            "1.0.5",
            "1.0.4",
            "1.0.3",
            "1.0.2",
            "1.0.1",
            "1.0.0",
            "1.0.0-rc2",
            "1.0.0-rc1"
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2020-26276.json"
          }
        }
      ],
      "modified": "2026-10-20T10:54:25.433669321Z",
      "provider": "osv",
      "references": [
        "https://github.com/fleetdm/fleet/blob/master/CHANGELOG.md#fleet-351-dec-14-2020",
        "https://github.com/fleetdm/fleet/security/advisories/GHSA-w3wf-cfx3-6gcx",
        "https://github.com/mattermost/xml-roundtrip-validator",
        "https://mattermost.com/blog/coordinated-disclosure-go-xml-vulnerabilities",
        "https://github.com/fleetdm/fleet/commit/57812a532e5f749c8e18c6f6a652eca65c083607"
      ],
      "provider_metadata": {}
    },
    "related_cves": [
      {
        "value": "CVE-2020-26276",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 385341,
  "published_at": "2020-12-17T20:15:13.76+00:00"
}