CVE-2026-75588

Mattermost Desktop App plugin popout scheme validation bypass

Published Sep 17, 2026 CVSS 3.1 · 2.6 Low EPSS < 1% KEV · Not listed
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

Remediation

Vendor Solution

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

Tracking

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Advisories

No advisories available
References
History
Type Values Removed Values Added
First Time appeared Mattermost mattermost Desktop
CPEs cpe:2.3:a:mattermost:mattermost_desktop:*:*:*:*:*:*:*:*
Vendors & Products Mattermost mattermost Desktop
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'}

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'}

Weaknesses

Sources

Status
PUBLISHED
Assigner
Mattermost
Published
Updated
Sep 17, 2026, 7:22 PM
Reserved
Aug 17, 2026, 10:19 PM
Status
Analyzed
Published
Sep 17, 2026, 4:17 PM
Modified
Oct 13, 2026, 12:02 PM