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

High severity GitHub Reviewed Published May 24, 2022 to the GitHub Advisory Database • Updated Nov 20, 2025

Package

gomod github.com/mattermost/mattermost-server (Go)

Affected versions

< 5.1.0

Patched versions

5.1.0

Description

An issue was discovered in Mattermost Server before 5.1.0. It allows attackers to cause a denial of service via the invite_people slash command.

References

Published by the National Vulnerability Database Jun 19, 2020
Published to the GitHub Advisory Database May 24, 2022
Reviewed Nov 20, 2025
Last updated Nov 20, 2025

Severity

High

CVSS overall score

This score calculates overall vulnerability severity from 0 to 10 and is based on the Common Vulnerability Scoring System (CVSS).
/ 10

CVSS v3 base metrics

Attack vector
Network
Attack complexity
Low
Privileges required
None
User interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

CVSS v3 base metrics

Attack vector: More severe the more the remote (logically and physically) an attacker can be in order to exploit the vulnerability.
Attack complexity: More severe for the least complex attacks.
Privileges required: More severe if no privileges are required.
User interaction: More severe when no user interaction is required.
Scope: More severe when a scope change occurs, e.g. one vulnerable component impacts resources in components beyond its security scope.
Confidentiality: More severe when loss of data confidentiality is highest, measuring the level of data access available to an unauthorized user.
Integrity: More severe when loss of data integrity is the highest, measuring the consequence of data modification possible by an unauthorized user.
Availability: More severe when the loss of impacted component availability is highest.
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

EPSS score

Exploit Prediction Scoring System (EPSS)

This score estimates the probability of this vulnerability being exploited within the next 30 days. Data provided by FIRST.
(65th percentile)

Weaknesses

Uncontrolled Resource Consumption

The product does not properly control the allocation and maintenance of a limited resource, thereby enabling an actor to influence the amount of resources consumed, eventually leading to the exhaustion of available resources. Learn more on MITRE.

CVE ID

CVE-2018-21258

GHSA ID

GHSA-5mh6-p63g-3mv5

Source code

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