Answer in brief
CVE-2026-82920 records a Medium severity (CVSS 5.5) vulnerability in Mattermost ABAC parent policy bypass via policy update endpoint. The current sources do not mark it as known exploited. The current feed maps Mattermost/Mattermost (generic), Mattermost/Mattermost (generic). Check affected ranges and fixed versions before updating.
Analysis pending evidence review
HOL Guard separates source facts from reviewed analysis. See the methodology.
CVSS is 5.5. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.
Analysis status
Analysis pending evidence review
Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.
The current feed maps Mattermost/Mattermost (generic), Mattermost/Mattermost (generic). Check affected ranges and fixed versions before updating.
| Product | Affected versions | Fixed versions |
|---|---|---|
| cpe:2.3:a:mattermost:mattermost_server:*:*:*:*:*:*:*:* | Not reported | Not reported |
| Package | Affected range | Fixed version |
|---|---|---|
| Mattermost/Mattermostgeneric | 11.9.0 || 11.8.0 || 11.7.0 | Not reported |
| Mattermost/Mattermostgeneric | >=11.9.0 <=11.9.0 || >=11.8.0 <=11.8.4 || >=11.7.0 <=11.7.7 | Not reported |
Published upstream
Sep 14, 2026
Evidence: source:cvelist:source_dates:source-dates:recordSource modified
Oct 7, 2026
Evidence: source:cvelist:source_dates:source-dates:recordFirst seen by HOL
Sep 14, 2026
Mattermost versions 11.9.x <= 11.9.0, 11.8.x <= 11.8.4, 11.7.x <= 11.7.7 fail to enforce authorization boundaries on the access control policy update endpoint which allows a channel or team administrator to detach a system-assigned ABAC parent policy via a crafted PUT /api/v4/access_control_policies request with an empty imports list.. Mattermost Advisory ID: MMSA-2026-00724
Quoted source text, attributed separately from HOL analysis.