What’s Vulnerable › Vulnerabilities

CVE-2019-20859

• Severity: high (CVSS 7.5 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 5.15.0. Login access control can be bypassed via crafted input.

Affected products

• Mattermost: before 4.10.8; from 5.7.0 before 5.7.3; from 5.8.0 before 5.8.1; 5.9.0-rc1, 5.9.0-rc2, 5.9.0-rc3, 5.9.0-rc4 — fixed in 4.10.8, 5.7.3, 5.8.1

How to fix

Upgrade to a fixed version: Mattermost 4.10.8, 5.7.3, 5.8.1. Check the vendor advisory for mitigations.

References

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

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