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Mattermost Open Redirect vulnerability

Low severity GitHub Reviewed Published Sep 15, 2025 to the GitHub Advisory Database • Updated Sep 16, 2025

Package

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

Affected versions

>= 10.5.0, < 10.5.10

Patched versions

10.5.10
gomod github.com/mattermost/mattermost/server/v8 (Go)
< 8.0.0-202508080704-39bd251fe4f600
8.0.0-202508080704-39bd251fe4f600

Description

Mattermost versions 10.5.x <= 10.5.9 fail to properly validate redirect URLs which allows attackers to redirect users to malicious sites via crafted OAuth login URLs.

References

Published by the National Vulnerability Database Sep 15, 2025
Published to the GitHub Advisory Database Sep 15, 2025
Last updated Sep 16, 2025
Reviewed Sep 16, 2025

Severity

Low

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
High
Privileges required
None
User interaction
Required
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:H/PR:N/UI:R/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.
(7th percentile)

Weaknesses

URL Redirection to Untrusted Site ('Open Redirect')

A web application accepts a user-controlled input that specifies a link to an external site, and uses that link in a Redirect. This simplifies phishing attacks. Learn more on MITRE.

CVE ID

CVE-2025-9084

GHSA ID

GHSA-hm95-jx66-g2gh

Source code

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