CVE-2018-21256

4.3 mediumEPSS 0.6%

An issue was discovered in Mattermost Server before 5.1. It allows attackers to bypass intended access restrictions (for group-message channel creation) via the Group message slash command.

Severity

CVSS 3.1

4.3 medium

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:N

EPSS: 0.6% chance of exploitation in the next 30 days; higher than 49% of CVEs (scores of 2026-10-31)
CWE: CWE-732
Published: 2020-06-19
Modified: 2026-06-17
Record from: the NVD, synced 2026-10-19

Affected

mattermost:mattermost_server

References

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

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