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Mattermost Server's OAuth 2.0 service is vulnerable to attack through Missing Authorization

Moderate severity GitHub Reviewed Published May 24, 2022 to the GitHub Advisory Database • Updated Oct 24, 2025

Package

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

Affected versions

< 4.3.3
>= 4.4.0-rc1, < 4.4.3

Patched versions

4.3.3
4.4.3

Description

An issue was discovered in Mattermost Server before 4.4.3 and 4.3.3. Attackers could reconfigure an OAuth app in some cases where Mattermost is an OAuth 2.0 service provider.

References

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

Severity

Moderate

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
Low
User interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
Low
Availability
None

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:L/UI:N/S:U/C:N/I:L/A:N

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.
(37th percentile)

Weaknesses

Missing Authorization

The product does not perform an authorization check when an actor attempts to access a resource or perform an action. Learn more on MITRE.

CVE ID

CVE-2017-18872

GHSA ID

GHSA-hgrp-fgm8-56g8

Source code

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