Detections
Analytics

Mattermost Server 10.11.x < 10.11.14 / 11.4.x < 11.4.4 / 11.5.x < 11.5.2 Vulnerability (MMSA-2026-00597)

medium Nessus Plugin ID 321516

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 enforce slash command trigger-word uniqueness during command updates which allows an authenticated team member with Manage Own Slash Commands permission to hijack and impersonate existing system or custom slash commands via editing their own slash command trigger to an already-registered trigger through the command update API. (CVE-2026-28732)

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, 11.4.4, 11.5.2, 11.6.0 or later.

See Also

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

Plugin Details

Severity: Medium

ID: 321516

File Name: mattermost_server_MMSA-2026-00597.nasl

Version: 1.1

Type: Remote

Family: CGI abuses

Published: 6/18/2026

Updated: 6/18/2026

Supported Sensors: Nessus

Risk Information

VPR

Risk Factor: Low

Score: 2.2

CVSS v2

Risk Factor: Medium

Base Score: 4

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

CVSS Score Source: CVE-2026-28732

CVSS v3

Risk Factor: Medium

Base Score: 4.3

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

Vulnerability Information

CPE: cpe:/a:mattermost:mattermost_server

Required KB Items: installed_sw/Mattermost Server

Patch Publication Date: 4/15/2026

Vulnerability Publication Date: 5/18/2026

Reference Information

CVE: CVE-2026-28732