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MEDIUM severity

Mattermost Fails to Sanitize File NamesGHSA-pj6f-rc94-gw53

MEDIUM

GHSA-pj6f-rc94-gw53 is a medium-severity (CVSS 4.3) Path Traversal vulnerability in github.com/mattermost/mattermost-server. A fix is available for github.com/mattermost/mattermost-server — see the affected versions and patch details below.

Also known asCVE-2025-6465GO-2025-3910
Published
Updated
Affected
5 pkgs
Patched
5 / 5
Exploits
None indexed
Exploitation data as of Nov 7, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

Exploitation Status

No confirmed exploitation observed yet

  • CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.

Exploitation and automatability from CISA’s SSVC triage for GHSA-pj6f-rc94-gw53.

EPSS Exploitation Probability

via FIRST.org ↗
0.8%probability of exploitation in next 30 days
Lower Risk0.00%
Lower risk than most CVEs56th percentile — riskier than 56% of all scored CVEsHighest risk
0.00%0.42%0.84%1.26%0.1%0.8%May 26Sep 26Nov 26

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

How urgent is this, really

Where this sits among everything scored

Real-World Exposure

5 pkgs affected
🐹github.com/mattermost/mattermost-server🐹github.com/mattermost/mattermost-server🐹github.com/mattermost/mattermost-server🐹github.com/mattermost/mattermost-server🐹github.com/mattermost/mattermost/server/v8

Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects Go packages — download data is not available via public APIs for these ecosystems.

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.

Affected Packages

5 total 5 fixed
EcosystemPackageVulnerable rangeFix
🐹Gogithub.com/mattermost/mattermost-server≥ 10.8.0&&< 10.8.410.8.4go get github.com/mattermost/mattermost-server@v10.8.4
🐹Gogithub.com/mattermost/mattermost-server≥ 10.5.0&&< 10.5.910.5.9go get github.com/mattermost/mattermost-server@v10.5.9
🐹Gogithub.com/mattermost/mattermost-server≥ 10.9.0&&< 10.9.410.9.4go get github.com/mattermost/mattermost-server@v10.9.4
🐹Gogithub.com/mattermost/mattermost-server≥ 10.10.0&&< 10.10.110.10.1go get github.com/mattermost/mattermost-server@v10.10.1
🐹Gogithub.com/mattermost/mattermost/server/v8all versions8.0.0-20250708173752-d6b35c41f0ae5go get github.com/mattermost/mattermost/server/v8@v8.0.0-20250708173752-d6b35c41f0ae5

Affected Products

1 product · 4 configurations
Application
mattermost servermattermost
≥ 10.9.0 && < 10.9.4
1 version
10.10.0

Detection & mitigation playbook

Open-source dependency

  1. Detect

    Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for github.com/mattermost/mattermost-server, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

  2. Fix

    Update github.com/mattermost/mattermost-server to 10.8.4 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-pj6f-rc94-gw53 is resolved across your whole dependency graph.

  3. Workarounds

    Resolve every user-supplied path to its canonical form and reject anything that escapes the intended directory, and run the component under an account that has no read or write access outside the directory it legitimately serves.

Frequently Asked Questions

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.
O3 Security · Impact-Aware SCA

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Mattermost Fails to Sanitize File Names (Medium 4.3)