Detections
Analytics

Mattermost Server 10.11.x <= 10.11.13 / 11.3.x < 11.3.3 / 11.4.x < 11.4.3 / 11.5.x < 11.5.1 / 11.6.0 Multiple Vulnerabilities (MMSA-2026-00624 / MMSA-2026-00625)

medium Nessus Plugin ID 310112

Synopsis

The remote host is affected by multiple vulnerabilities.

Description

The version of Mattermost Server installed on the remote host is affected by multiple vulnerabilities:

 - Mattermost versions 10.11.x <= 10.11.12, 11.5.x <= 11.5.0, 11.4.x <= 11.4.2, 11.3.x <= 11.3.2 fail to enforce atomic single-use consumption of guest magic link tokens, which allows an attacker with access to a valid magic link to establish multiple independent authenticated sessions via concurrent requests.
 Mattermost Advisory ID: MMSA-2026-00624. (CVE-2026-3590)

 - Mattermost versions 10.11.x <= 10.11.12, 11.5.x <= 11.5.0, 11.4.x <= 11.4.2, 11.3.x <= 11.3.2 fail to validate CSRF tokens on an authentication endpoint which allows an attacker to update a user's authentication method via a CSRF attack by tricking a user into visiting a malicious page. Mattermost Advisory ID: MMSA-2026-00625. (CVE-2026-28741)

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

Solution

Upgrade to Mattermost Server version 10.11.13, 11.3.3, 11.4.3, 11.5.1, 11.6.0 or later.

See Also

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

Plugin Details

Severity: Medium

ID: 310112

File Name: mattermost_server_MMSA-2026-00624_MMSA-2026-00625.nasl

Version: 1.1

Type: Remote

Family: CGI abuses

Published: 4/24/2026

Updated: 4/24/2026

Supported Sensors: Nessus

Risk Information

VPR

Risk Factor: Medium

Score: 6.0

CVSS v2

Risk Factor: Medium

Base Score: 6.4

Temporal Score: 4.7

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

CVSS Score Source: CVE-2026-28741

CVSS v3

Risk Factor: Medium

Base Score: 6.8

Temporal Score: 5.9

Vector: CVSS:3.0/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/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: 3/16/2026

Vulnerability Publication Date: 4/15/2026

Reference Information

CVE: CVE-2026-28741, CVE-2026-3590

IAVA: 2026-A-0365