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Mattermost Server 10.11.x < 10.11.14 / 11.5.x < 11.5.2 Vulnerability (MMSA-2025-00552)

medium Nessus Plugin ID 321515

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Synopsis

The remote host is affected by a vulnerability.

Description

The version of Mattermost Server installed on the remote host is affected by a vulnerability:

 - Mattermost fails to check if team_id was being changed when updating playbooks, allowing users with only Manage Playbook Configurations permission to change a playbook's team, bypassing manage members restriction via PUT api. (CVE-2026-4286)

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 10.11.14, 11.5.2, 11.6.0 or later.

See Also

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

Plugin Details

Severity: Medium

ID: 321515

File Name: mattermost_server_MMSA-2025-00552.nasl

Version: 1.3

Type: Remote

Family: CGI abuses

Published: 6/18/2026

Updated: 6/24/2026

Supported Sensors: Nessus

Risk Information

VPR

Risk Factor: Low

Score: 1.2

Percentile: 0.01

CVSS v2

Risk Factor: Medium

Base Score: 4

Temporal Score: 3

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

CVSS Score Source: CVE-2026-4286

CVSS v3

Risk Factor: Medium

Base Score: 4.3

Temporal Score: 3.8

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

Temporal Vector: CVSS:3.0/E:U/RL:O/RC:C

Vulnerability Information

CPE: cpe:/a:mattermost:mattermost_server

Required KB Items: installed_sw/Mattermost Server

Exploit Ease: No known exploits are available

Patch Publication Date: 4/15/2026

Vulnerability Publication Date: 5/18/2026

Reference Information

CVE: CVE-2026-4286

IAVA: 2026-A-0604