CVE-2024-39839: mattermost server Access Control Flaw

Description

Mattermost versions 9.9.x <= 9.9.0, 9.5.x <= 9.5.6, 9.7.x <= 9.7.5, 9.8.x <= 9.8.1 fail to disallow users to set their own remote username, when shared channels were enabled, which allows a user on a remote to set their remote username prop to an arbitrary string, which would be then synced to the local server as long as the user hadn't been synced before.

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CVSS v3.1 Score

4.3

MEDIUM

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:N

Weakness Type (CWE)

CWE-284 CWE-284

Affected Products

Vendor	Product	Versions
mattermost	mattermost_server	9.5.0 — 9.5.7
mattermost	mattermost_server	9.7.0 — 9.7.6
mattermost	mattermost_server	9.8.0 — 9.8.2
mattermost	mattermost_server	All

References

Advisories & Patches

https://mattermost.com/security-updates

Frequently Asked Questions

What is CVE-2024-39839? +

Mattermost versions 9.9.x <= 9.9.0, 9.5.x <= 9.5.6, 9.7.x <= 9.7.5, 9.8.x <= 9.8.1 fail to disallow users to set their own remote username, when shared channels were enabled, which allows a user on a remote to set their remote username prop to an arbitrary string, which would be then synced to the local server as long as the user hadn't been synced before. It has a CVSS v3.1 base score of 4.3 (MEDIUM).

How severe is CVE-2024-39839? +

CVE-2024-39839 has a CVSS v3.1 score of 4.3 out of 10, rated MEDIUM. This is a medium-severity vulnerability that should be remediated as part of regular maintenance.

What products are affected by CVE-2024-39839? +

CVE-2024-39839 affects products from mattermost, specifically: mattermost_server. Check the affected products table above for specific version ranges.

How do I check if I'm vulnerable to CVE-2024-39839? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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