Detections
Analytics

Mattermost Server 10.11.x < 10.11.23 / 11.7.x < 11.7.8 / 11.8.x < 11.8.5 / 11.9.x < 11.9.1 Incorrect Authorization (MMSA-2026-00702)

medium Nessus Plugin ID 350091

Synopsis

The remote host is affected by an incorrect authorization vulnerability.

Description

The version of Mattermost Server installed on the remote host is affected by a vulnerability as referenced in the MMSA-2026-00702 advisory.

 - Mattermost versions 11.9.x <= 11.9.0, 11.8.x <= 11.8.4, 11.7.x <= 11.7.7, 10.11.x <= 10.11.22 fail to sanitize Team objects returned by the data retention teams endpoint which allows an authenticated user holding only the read-only Data Retention Policy permission to obtain a private team's secret invite_id and email, and use it to join the team without authorization, via GET /api/v4/data_retention/policies/{policy_id}/teams. Mattermost Advisory ID: MMSA-2026-00702.
 (CVE-2026-91181)

Note that Nessus has not tested for this issue but has instead relied only on the application's self-reported version number.

Solution

Upgrade to Mattermost Server version 10.11.23, 11.7.8, 11.8.5, 11.9.1, 11.10.0 or later.

See Also

https://docs.mattermost.com/security-guide/security-updates

https://mattermost.com/security-updates/

Plugin Details

Severity: Medium

ID: 350091

File Name: mattermost_server_MMSA-2026-00702.nasl

Version: 1.1

Type: Remote

Family: CGI abuses

Published: 9/25/2026

Updated: 9/25/2026

Supported Sensors: Nessus

Risk Information

VPR

Risk Factor: Medium

Score: 4.3

Percentile: 53.45

CVSS v2

Risk Factor: High

Base Score: 7.7

Vector: CVSS2#AV:N/AC:L/Au:M/C:C/I:C/A:N

CVSS Score Source: CVE-2026-91181

CVSS v3

Risk Factor: Medium

Base Score: 6.5

Vector: CVSS:3.0/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:N

Vulnerability Information

CPE: cpe:/a:mattermost:mattermost_server

Required KB Items: installed_sw/Mattermost Server

Patch Publication Date: 9/14/2026

Vulnerability Publication Date: 9/14/2026

Reference Information

CVE: CVE-2026-91181

IAVA: 2026-A-1047