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Critical

Security advisory

Type: advisorySources: OSVCVE: CVE-2017-18920

An issue was discovered in Mattermost Server before 3.6.2. The WebSocket feature does not follow the Same Origin Policy.

Products
Not specified
Affected versions
Not specified
Fixed versions
Not specified
CVEs
CVE-2017-18920
Confirmed fixed CVEs
Not specified
Updated in this feed
1 Nov 2026, 05:23 UTC · Revision 1

Source evidence

CVE-2017-18920

core-osv · Original source

Published 19 Jun 2020, 20:15 UTC

An issue was discovered in Mattermost Server before 3.6.2. The WebSocket feature does not follow the Same Origin Policy.

osv:CVE-2017-18920
Complete source record
{
  "id": "cb6d5a99f7e36d40c353eb59c703165e824a61c59a9744a0e7c4e7f6e77a6077",
  "url": "https://osv.dev/vulnerability/CVE-2017-18920",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "CVE-2017-18920",
    "summary": "An issue was discovered in Mattermost Server before 3.6.2. The WebSocket feature does not follow the Same Origin Policy.",
    "evidence": "osv:CVE-2017-18920",
    "products": [],
    "severity": "critical",
    "structured": {
      "id": "CVE-2017-18920",
      "aliases": [
        "CVE-2017-18920"
      ],
      "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/mattermost/mattermost",
              "type": "GIT",
              "events": [
                {
                  "introduced": "0"
                },
                {
                  "fixed": "1a9891f0f5671551d28be54a99155b907480cc5c"
                }
              ],
              "database_specific": {
                "extracted_events": [
                  {
                    "cpe": "cpe:2.3:a:mattermost:mattermost_server:*:*:*:*:*:*:*:*",
                    "range": [
                      {
                        "introduced": "0"
                      },
                      {
                        "fixed": "3.6.2"
                      }
                    ],
                    "source": "CPE_RANGE"
                  }
                ]
              }
            }
          ],
          "versions": [
            "v3.6.1",
            "v3.6.0",
            "v0.5.0"
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2017-18920.json"
          }
        }
      ],
      "modified": "2026-10-24T10:30:27.935041915Z",
      "provider": "osv",
      "references": [
        "https://mattermost.com/security-updates/"
      ],
      "provider_metadata": {}
    },
    "related_cves": [
      {
        "value": "CVE-2017-18920",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 431939,
  "published_at": "2020-06-19T20:15:12.71+00:00"
}