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Mattermost Fails to Sanitize File Names

Moderate severity GitHub Reviewed Published Aug 21, 2025 to the GitHub Advisory Database • Updated Aug 29, 2025

Package

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

Affected versions

>= 10.8.0, <= 10.8.3
>= 10.5.0, <= 10.5.8
>= 10.9.0, <= 10.9.3
= 10.10.0

Patched versions

10.8.4
10.5.9
10.9.4
10.10.1
gomod github.com/mattermost/mattermost/server/v8 (Go)
< 8.0.0-20250708173752-d6b35c41f0ae5
8.0.0-20250708173752-d6b35c41f0ae5

Description

Mattermost versions 10.8.x <= 10.8.3, 10.5.x <= 10.5.8, 10.10.x <= 10.10.0, 10.9.x <= 10.9.3 fail to sanitize file names which allows users with file upload permission to overwrite file attachment thumbnails via path traversal in file streaming APIs.

References

Published by the National Vulnerability Database Aug 21, 2025
Published to the GitHub Advisory Database Aug 21, 2025
Reviewed Aug 22, 2025
Last updated Aug 29, 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.
(16th percentile)

Weaknesses

Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')

The product uses external input to construct a pathname that is intended to identify a file or directory that is located underneath a restricted parent directory, but the product does not properly neutralize special elements within the pathname that can cause the pathname to resolve to a location that is outside of the restricted directory. Learn more on MITRE.

CVE ID

CVE-2025-6465

GHSA ID

GHSA-pj6f-rc94-gw53

Source code

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