CVE-2026-9816

CVE CVE-2026-9816EUVD EUVD-2026-60540Published 2026-08-17T22:05:24.000ZLast changed 2026-08-18T15:26:07.000ZCVSS 8.3

What the advisory describes

Mattermost versions 11.7.x <= 11.7.6, 10.11.x <= 10.11.21, 11.8.x <= 11.8.3 fail to validate BoardMember.Scheme* fields server-side on insert and archive-import paths which allows a board editor or non-guest team member to grant board admin to arbitrary users via POST /api/v2/boards/{boardID}/members and POST /api/v2/teams/{teamID}/archive/import.. Mattermost Advisory ID: MMSA-2026-00685

Source: EUVD (ENISA), in the words of the advisory.

Products the advisory names

These come from the advisory itself, not from any check we performed.

Mattermost — Mattermost 11.8.0 ≤11.8.3; 10.11.0 ≤10.11.21; 11.7.0 ≤11.7.6

The versions shown are the advisory's own. Patchlage compares no version numbers and derives no judgement from them — which version is installed is something a person has to look up.

Carried in the product catalogue

An estate covering these products can be recorded in Patchlage. An advisory about them appears in the next morning's situation report.

Mattermost — Mattermost

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