What’s Vulnerable › Vulnerabilities

CVE-2019-20889

• Severity: medium (CVSS 5.3 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.8% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2020-06-19 · updated 2026-06-17
• Weakness: CWE-276

Description

An issue was discovered in Mattermost Server before 5.7, 5.6.3, 5.5.2, and 4.10.5. It mishandles permissions for user-access token creation.

Affected products

• Mattermost: from 4.10.0 before 4.10.5; from 5.5.0 before 5.5.2; from 5.6.0 before 5.6.3; 5.7.0-rc1, 5.7.0-rc2, 5.7.0-rc3, 5.7.0-rc4, 5.7.0-rc5, 5.7.0-rc6 — fixed in 4.10.5, 5.5.2, 5.6.3

How to fix

Upgrade to a fixed version: Mattermost 4.10.5, 5.5.2, 5.6.3. Check the vendor advisory for mitigations.

References

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

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