CVE-2026-10527Network attack vector

Privilege escalation via stale Board Admin state

Published Aug 17, 2026 · Updated Aug 17, 2026

Incorrect authorization in Mattermost before 10.11.22, 11.7.7, and 11.8.4 lets remote authenticated users keep Boards admin access after demotion. The Boards plugin does not reconcile its SchemeAdmin-derived Board Admin state with the user's current system role, so a user demoted to System Guest still passes authorization for admin-only Boards REST API and UI operations. Exploitation requires an existing authenticated account that previously held the relevant Boards administrative state; the exposed impact is unauthorized Boards administration rather than full Mattermost system administration.

CVSS severity6.3
Medium
EPSS probability0.15%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Incorrect authorization in Mattermost before 10.11.22, 11.7.7, and 11.8.4 lets remote authenticated users keep Boards admin access after demotion. The Boards plugin does not reconcile its SchemeAdmin-derived Board Admin state with the user's current system role, so a user demoted to System Guest still passes authorization for admin-only Boards REST API and UI operations. Exploitation requires an existing authenticated account that previously held the relevant Boards administrative state; the exposed impact is unauthorized Boards administration rather than full Mattermost system administration.

The record

CVE
CVE-2026-10527
Published
Aug 17, 2026
Updated
Aug 17, 2026
Vendor
Mattermost
Product
Mattermost
Classifications
CWE-863
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Aug 17, 2026CVE publishedPublication date reported by the CVE source.
  2. Aug 17, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=10.11.0 <=10.11.21
  2. Affected versionversion=11.7.0 <=11.7.6
  3. Affected versionversion=11.8.0 <=11.8.3

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

Mattermost · Mattermostversion=10.11.0 <=10.11.21; version=11.7.0 <=11.7.6; version=11.8.0 <=11.8.3

Published CVSS scores

6.3MattermostCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:L

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-863Incorrect Authorization

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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