Mattermost versions 11.10.x <= 11.10.0, 11.7.x <= 11.7.9, 11.9.x <= 11.9.1, 11.8.x <= 11.8.5 fail to enforce DM/GM check on server side which allows an authenticated user to quarantine a post belonging to DM or GM via direct API call.. Mattermost Advisory ID: MMSA-2026-00756

No CVSS v4.0

Attack Vector Network

Attack Complexity High

Privileges Required Low

Scope Unchanged

Confidentiality Impact High

Integrity Impact Low

Availability Impact Low

User Interaction None

No CVSS v3.0

No CVSS v2

This CVE is not in the KEV list.

The EPSS score is 0.0015.

Exploitation none

Automatable no

Technical Impact partial

Default status is the baseline for the product, each version can override it (e.g. patched versions marked unaffected).

Vendor Product Default status Versions
Mattermost Mattermost unaffected
Version Status Constraints
11.10.0 affected ≤ 11.10.0
11.7.0 affected ≤ 11.7.9
11.9.0 affected ≤ 11.9.1
11.8.0 affected ≤ 11.8.5
11.11.0 unaffected —
11.10.1 unaffected —
11.7.10 unaffected —
11.9.2 unaffected —
11.8.6 unaffected —

No data.

No data.

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No data.

Project Subscriptions

No data.

Advisories

No advisories yet.

Fixes

Solution

Update Mattermost to versions 11.11.0, 11.10.1, 11.7.10, 11.9.2, 11.8.6 or higher.

Workaround

No workaround given by the vendor.

References
Link Providers
https://mattermost.com/security-updates cve-icon cve-icon
History

Fri, 16 Oct 2026 13:30:00 +0000

Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}

Fri, 16 Oct 2026 07:15:00 +0000

Type Values Removed Values Added
Description Mattermost versions 11.10.x <= 11.10.0, 11.7.x <= 11.7.9, 11.9.x <= 11.9.1, 11.8.x <= 11.8.5 fail to enforce DM/GM check on server side which allows an authenticated user to quarantine a post belonging to DM or GM via direct API call.. Mattermost Advisory ID: MMSA-2026-00756
Title Missing server side validation allowed user to quarantine a DM and GM post
Weaknesses CWE-862
References
Metrics cvssV3_1

{'score': 6.4, 'vector': 'CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:L/A:L'}

Projects

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cve-icon MITRE

Status: PUBLISHED

Assigner: Mattermost

Published:

Updated: 2026-10-16T11:59:42.771Z

Reserved: 2026-08-04T09:13:11.334Z

Link: CVE-2026-18795

cve-icon Vulnrichment

Updated: 2026-10-16T11:59:37.292Z

cve-icon NVD

Status : Received

Published: 2026-10-16T07:17:12.407

Modified: 2026-10-16T12:16:38.867

Link: CVE-2026-18795

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

Updated: 2026-10-16T15:30:14Z

Weaknesses