Is CVE-2026-10527 being exploited?

No public exploit is currently tracked.

How severe is CVE-2026-10527?

CVE-2026-10527 has a CVSS v3 severity of MEDIUM (6.3).

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CVE-2026-10527

Description

Mattermost versions 11.7.x <= 11.7.6, 10.11.x <= 10.11.21, 11.8.x <= 11.8.3 fails to reconcile SchemeAdmin flags with a user's current role which allows a user demoted to System Guest to retain Board Admin privileges and perform admin-only operations via the Boards REST API or UI.. Mattermost Advisory ID: MMSA-2026-00691