Detections
Analytics

Mattermost Server 10.11.x < 10.11.15 / 11.4.x < 11.4.5 / 11.5.x < 11.5.4 / 11.6.x < 11.6.1 Path Traversal (MMSA-2026-00640)

critical Nessus Plugin ID 317392

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Synopsis

The remote host is affected by a path traversal vulnerability.

Description

The version of Mattermost Server installed on the remote host is affected by a vulnerability as referenced in the MMSA-2026-00640 advisory.

 - Mattermost Server fails to check the integration URL for path traversal which allows a malicious authenticated user to call an arbitrary API via a system admin auth token via path traversal in an integration action URL. Mattermost Advisory ID: MMSA-2026-00640. (CVE-2026-4858)

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 10.11.15, 11.4.5, 11.5.4, 11.6.1, 11.7.0, or later.

See Also

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

Plugin Details

Severity: Critical

ID: 317392

File Name: mattermost_server_MMSA-2026-00640.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: High

Score: 7.3

CVSS v2

Risk Factor: High

Base Score: 9

Temporal Score: 6.7

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

CVSS Score Source: CVE-2026-4858

CVSS v3

Risk Factor: Critical

Base Score: 9.9

Temporal Score: 8.6

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

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: 4/17/2026

Reference Information

CVE: CVE-2026-4858