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CVE-2026-75588

Mattermost Desktop App plugin popout scheme validation bypass

CVSS 3.1 2.6 LOWCheck source for fixed versionsKEV status unknown

Original advisory

cve-program · CVE-2026-75588

Published

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

Read the publisher's advisory

Affected versions, risk and source history

cve-program · CVE-2026-75588

Published

Mattermost

Vendor product

Publisher's version information

Shown as published. These rules are not interpreted as NuGet package version ranges.

{
                    "defaultStatus": "unaffected",
                    "product": "Mattermost",
                    "vendor": "Mattermost",
                    "versions": [
                        {
                            "lessThanOrEqual": "6.2.2",
                            "status": "affected",
                            "version": "0",
                            "versionType": "semver"
                        },
                        {
                            "version": "6.3.0",
                            "status": "unaffected"
                        },
                        {
                            "version": "6.2.3.0",
                            "status": "unaffected"
                        }
                    ]
                }

Original source record · Cite this exact observation · Complete original publisher JSON