Detections
Analytics

Mattermost Server 10.11.x < 10.11.16 / 11.5.x < 11.5.5 / 11.6.x < 11.6.2 Multiple Vulnerabilities (MMSA-2026-00616 / MMSA-2026-00649 / MMSA-2026-00655 / MMSA-2026-00656 / MMSA-2026-00661 / MMSA-2026-00662 / MMSA-2026-00665)

high Nessus Plugin ID 321514

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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 fails to require role-management authorization when setting the scheme_admin flag on group syncable link and patch endpoints, which allows a user with group-link permissions to escalate themselves and group members to team or channel admin via crafted API requests. (CVE-2026-7387)

 - Mattermost fails to sanitize FileInfo.Name received from federated peers during shared channel file sync, which allows an attacker who controls a federated server to write files to arbitrary locations within the target server's filestore via path traversal sequences in the filename field. (CVE-2026-6961)

 - Mattermost fails to require system-level permission when patching protected default system roles, which allows authenticated users with delegated user-management permissions to escalate privileges by altering built-in role permissions via the role patch API. (CVE-2026-6739)

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 10.11.16, 11.5.5, 11.6.2, 11.7.0 or later.

See Also

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

Plugin Details

Severity: High

ID: 321514

File Name: mattermost_server_MMSA-2026-00616_00649_00655_00656_00661_00662_00665.nasl

Version: 1.4

Type: Remote

Family: CGI abuses

Published: 6/18/2026

Updated: 6/24/2026

Supported Sensors: Nessus

Risk Information

VPR

Risk Factor: Medium

Score: 4.9

Percentile: 57.96

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-2026-7387

CVSS v3

Risk Factor: High

Base Score: 7.2

Temporal Score: 6.3

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

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

CVSS Score Source: CVE-2026-6739

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: 5/13/2026

Vulnerability Publication Date: 6/12/2026

Reference Information

CVE: CVE-2026-3433, CVE-2026-6046, CVE-2026-6689, CVE-2026-6739, CVE-2026-6961, CVE-2026-7184, CVE-2026-7387

IAVA: 2026-A-0604