Detections
Analytics

Mattermost Server 10.11.x < 10.11.17 / 11.5.x < 11.5.5 / 11.6.x < 11.6.2 Improper Authorization (MMSA-2026-00629)

medium Nessus Plugin ID 317393

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Synopsis

The remote host is affected by an improper authorization vulnerability.

Description

The version of Mattermost Server installed on the remote host is affected by a vulnerability as referenced in the MMSA-2026-00629 advisory.

 - Mattermost Server fails to validate team-level run_create permission against the target team when creating a playbook run which allows an authenticated team member to create runs in teams where they lack permission via specifying a different team ID in the run creation API request. Mattermost Advisory ID: MMSA-2026-00629.
 (CVE-2026-4055)

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 10.11.17, 11.5.5, 11.6.2, 11.7.0, or later.

See Also

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

Plugin Details

Severity: Medium

ID: 317393

File Name: mattermost_server_MMSA-2026-00629.nasl

Version: 1.2

Type: Remote

Family: CGI abuses

Published: 5/28/2026

Updated: 6/1/2026

Supported Sensors: Nessus

Risk Information

VPR

Risk Factor: Low

Score: 2.2

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-2026-4055

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: 5/15/2026

Vulnerability Publication Date: 4/20/2026

Reference Information

CVE: CVE-2026-4055