Critical
Security advisory
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
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"
}