Mattermost Desktop App versions <=6.2 6.2.2.0 fail to validate the URL scheme when checking whether a target URL is internal to the connected server, which allows a network-positioned attacker to load a plugin popout window over an insecure connection via a link using a downgraded URL scheme. Mattermost Advisory ID: MMSA-2026-00717
Advisories

No advisories yet.

Fixes

Solution

Update Mattermost Desktop App to versions 6.3.0, 6.2.3.0 or higher.


Workaround

No workaround given by the vendor.

References
History

Thu, 17 Sep 2026 20:30:00 +0000

Type Values Removed Values Added
First Time appeared Mattermost
Mattermost mattermost
Vendors & Products Mattermost
Mattermost mattermost
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}


Thu, 17 Sep 2026 15:30:00 +0000

Type Values Removed Values Added
Description Mattermost Desktop App versions <=6.2 6.2.2.0 fail to validate the URL scheme when checking whether a target URL is internal to the connected server, which allows a network-positioned attacker to load a plugin popout window over an insecure connection via a link using a downgraded URL scheme. Mattermost Advisory ID: MMSA-2026-00717
Title Mattermost Desktop App plugin popout scheme validation bypass
Weaknesses CWE-1287
References
Metrics cvssV3_1

{'score': 2.6, 'vector': 'CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:U/C:N/I:L/A:N'}


Projects

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cve-icon MITRE

Status: PUBLISHED

Assigner: Mattermost

Published:

Updated: 2026-09-17T19:22:50.101Z

Reserved: 2026-08-17T22:19:32.227Z

Link: CVE-2026-75588

cve-icon Vulnrichment

Updated: 2026-09-17T19:22:40.335Z

cve-icon NVD

Status : Received

Published: 2026-09-17T16:17:41.940

Modified: 2026-09-17T20:18:14.713

Link: CVE-2026-75588

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

Updated: 2026-09-17T19:56:41Z

Weaknesses