CVE-2026-21386 — Vulnetix

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CVE-2026-21386 PUBLISHED CVSS 4.300000190734863 MEDIUM

Mattermost fails to use consistent error responses when handling the /mute command

EPSS 0.03% · 9.2th percentile

Risk Scores

CVSS v3.1

4.300000190734863

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

EPSS Score

0.03%

9.2th percentile

Affected Products

Vendor	Product	Versions
Mattermost	Mattermost	11.3.0, 11.4.0, 11.3.1
github.com	mattermost/mattermost/server/v8	0, 0
mattermost	mattermost_server	11.2.0, 10.11.0, 11.3.0
github.com	mattermost/mattermost-server	0, 10.11.0-rc1, 11.2.0-rc1

Timeline

Mar 16, 2026 CVE Published
Mar 17, 2026 EPSS Score
Mar 18, 2026 EPSS Score
Mar 18, 2026 CVE Updated
Mar 19, 2026 EPSS Score
Mar 19, 2026 Security Advisory
Mar 20, 2026 EPSS Score
Mar 21, 2026 EPSS Score
Mar 22, 2026 EPSS Score
Mar 23, 2026 EPSS Score
Mar 24, 2026 EPSS Score
Mar 25, 2026 EPSS Score

References

MMSA-2026-00588 vendor-advisory
https://nvd.nist.gov/vuln/detail/CVE-2026-21386 advisory
https://github.com/mattermost/mattermost/commit/5bb5261c72faa476558a694c23581d24b734da41 url
https://github.com/mattermost/mattermost package

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