What’s Vulnerable › Vulnerabilities

CVE-2017-18920

• Severity: critical (CVSS 9.8 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 1.2% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2020-06-19 · updated 2026-06-17

Description

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

Affected products

• Mattermost: before 3.6.2 — fixed in 3.6.2

How to fix

Upgrade to a fixed version: Mattermost 3.6.2. Check the vendor advisory for mitigations.

References

• https://mattermost.com/security-updates/
• https://mattermost.com/security-updates/

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