Detections
Analytics

SCA: security update for github.com/mattermost/mattermost-server, github.com/mattermost/mattermost/server/v8 (GHSA-fg35-5rf6-qg3g)

medium Tenable Cloud Security Plugin ID 439494

Description

There are packages installed that are affected by a vulnerability referenced in the following CVE:

 - Mattermost versions 11.4.x <= 11.4.0, 11.3.x <= 11.3.1, 11.2.x <= 11.2.3, 10.11.x <= 10.11.11 fail to
 properly validate user identity in the OpenID {{IsSameUser()}} comparison logic, which allows an attacker
 to take over arbitrary user accounts via an overly permissive substring matching flaw in the user
 discovery flow.. Mattermost Advisory ID: MMSA-2026-00590 (CVE-2026-27656)

Solution

Update the github.com/mattermost/mattermost-server library and its related packages to version 10.11.12 or later.

See Also

https://github.com/advisories/GHSA-fg35-5rf6-qg3g

Plugin Details

Severity: Medium

ID: 439494

Version: Revision 1.6

Type: Local

Family: SCA Checks

Published: 3/31/2026

Updated: 7/2/2026

Supported Sensors: Tenable Cloud Security, Tenable Self-Hosted Container Security

Risk Information

VPR

Risk Factor: Medium

Score: 4.3

Percentile: 53.59

Vendor

Vendor Severity: Medium

CVSS v2

Risk Factor: High

Base Score: 7.7

Temporal Score: 5.7

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

CVSS Score Source: CVE-2026-27656

CVSS v3

Risk Factor: Medium

Base Score: 6.1

Temporal Score: 5.3

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

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

Vulnerability Information

Exploit Ease: No known exploits are available

Patch Publication Date: 3/25/2026

Vulnerability Publication Date: 3/25/2026

Reference Information

CVE: CVE-2026-27656

cwe: CWE-303