Mattermost Server is vulnerable to a Denial of Service attack through `invite_people` command

published 2020-06-19 6y ago modified 2026-06-17 4mo ago also GHSA-5mh6-p63g-3mv5 , GO-2025-4146 , EUVD-2018-13773

cvss: 7.5; version 3.1, NVD
cisa kev: Not listed; not in CISA's catalog
epss: 1.2%; EPSS 1.2% chance of exploitation in 30 days, percentile 67%
public exploits: 0; none known

An issue was discovered in Mattermost Server before 5.1. It allows attackers to cause a denial of service via the invite_people slash command.

Patch / fix

fixed in 3 distros 2 links 1

go github.com/mattermost/mattermost-server 5.1.0
go github.com/mattermost/mattermost-server/v5 5.1.0
mattermost mattermost_server 5.1.0

suse opensuse

govulncheck-vulndb SLE Module for Package Hub 15 SP6, openSUSE Leap 15.6 0.0.20251209T172047-150000.1.127.1

suse advisories SUSE-SU-2025:4395-1

govulncheck-vulndb openSUSE Leap 16.0 0.0.20260723T184607-160000.1.1

opensuse advisories openSUSE-SU-2026:21483-1

github.com/mattermost/mattermost@af615ff commit

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Exploit prediction

1.17% chance of exploitation in the next 30 days, higher than 67% of all scored CVEs (FIRST EPSS, 2026-11-09).

CVSS scores

assigned by	version	score	vector
NVD	3.1	7.5	CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
NVD	2.0	5.0	AV:N/AC:L/Au:N/C:N/I:N/A:P
GitHub	3.1	7.5	CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Affected packages

ecosystem	package	affected	fixed in
go	github.com/mattermost/mattermost-server	<5.1.0 all versions	5.1.0
go	github.com/mattermost/mattermost-server/v5	<5.1.0	5.1.0

Classification

Weakness

CWE-74 Improper Neutralization of Special Elements in Output Used by a Downstream Component
CWE-400 Uncontrolled Resource Consumption

References

github.com /mattermost/mattermost/commit/af615ffc24b774d76deef8c93282831432669dd8
web
mattermost.com /security-updates/
vendor-advisory
nvd.nist.gov /vuln/detail/CVE-2018-21258
advisory
github.com /mattermost/mattermost
package
mattermost.com /security-updates
web
github.com /advisories/GHSA-5mh6-p63g-3mv5
advisory

Sources

Fencer Intel keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.