What is CVE-2024-39839?

CVE-2024-39839 is a medium-severity vulnerability in Mattermost, classified under Improper Access Control. CVSS score: 4.3/10. Published 2024-08-01.

How severe is CVE-2024-39839?

Medium severity. CVSS v3 base score is 4.3 out of 10.

Is CVE-2024-39839 known to be exploited?

1 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.

Vulnerability in Mattermost

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.

EPSS: 0.003 (26.4th percentile) — read the EPSS interpretation.

CVSS v3 metric

CVSS v3 base score 4.3 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:N.

Affected products

Mattermost — versions 9.9.0, 9.5.0, 9.7.0
Mattermost Mattermost_server — versions 9.9.0

Weakness classification (CWE)

CWE-284 — Improper Access Control

Public proof-of-concept exploits

fkie-cad/nvd-json-data-feeds

References

responsibledisclosure@mattermost.com (Vendor Advisory)

Frequently asked questions

What is CVE-2024-39839?: CVE-2024-39839 is a medium-severity vulnerability in Mattermost, classified under Improper Access Control. CVSS score: 4.3/10. Published 2024-08-01.
How severe is CVE-2024-39839?: Medium severity. CVSS v3 base score is 4.3 out of 10.
Is CVE-2024-39839 known to be exploited?: 1 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.