CVE-2026-28759

Published: Mag 18, 2026 Last Modified: Mag 18, 2026
ExploitDB:
Other exploit source:
Google Dorks:
MEDIUM 4,3
Source: [email protected]
Attack Vector: network
Attack Complexity: low
Privileges Required: low
User Interaction: none
Scope: unchanged
Confidentiality: none
Integrity: low
Availability: none

Description

AI Translation Available

Mattermost versions 11.5.x <= 11.5.1, 10.11.x <= 10.11.13, 11.4.x <= 11.4.3 fail to validate that a remote cluster has access to a channel before processing membership removal requests during shared channel membership sync, which allows a malicious remote cluster to remove any user from any channel, including private channels, via crafted membership sync messages targeting channels the remote cluster is not authorized to access. Mattermost Advisory ID: MMSA-2026-00576

EPSS (Exploit Prediction Scoring System)

Trend Analysis

EPSS (Exploit Prediction Scoring System)

Prevede la probabilità di sfruttamento basata su intelligence sulle minacce e sulle caratteristiche della vulnerabilità.

EPSS Score
0,0003
Percentile
0,1th
Updated

EPSS Score Trend (Last 3 Days)

863

Incorrect Authorization

Incomplete
Abstraction: Class Structure: Simple
Common Consequences
Security Scopes Affected:
Confidentiality Integrity Access Control Availability
Potential Impacts:
Read Application Data Read Files Or Directories Modify Application Data Modify Files Or Directories Gain Privileges Or Assume Identity Bypass Protection Mechanism Execute Unauthorized Code Or Commands Dos: Crash, Exit, Or Restart Dos: Resource Consumption (Cpu) Dos: Resource Consumption (Memory) Dos: Resource Consumption (Other)
Applicable Platforms
Technologies: Web Server, Database Server, Not Technology-Specific
Likelihood of Exploit: High
View CWE Details
Application

Mattermost Server by Mattermost

Product Information
Vendor Mattermost
Product Mattermost Server
Version Range Affected
From 10.11.0 (inclusive)
To 10.11.14 (exclusive)
cpe:2.3:a:mattermost:mattermost_server:*:*:*:*:*:*:*:*
Common Platform Enumeration - Standardized vulnerability identification
Application

Mattermost Server by Mattermost

Product Information
Vendor Mattermost
Product Mattermost Server
Version Range Affected
From 11.5.0 (inclusive)
To 11.5.2 (exclusive)
cpe:2.3:a:mattermost:mattermost_server:*:*:*:*:*:*:*:*
Common Platform Enumeration - Standardized vulnerability identification
Application

Mattermost Server by Mattermost

Product Information
Vendor Mattermost
Product Mattermost Server
Version Range Affected
From 11.4.0 (inclusive)
To 11.4.4 (exclusive)
cpe:2.3:a:mattermost:mattermost_server:*:*:*:*:*:*:*:*
Common Platform Enumeration - Standardized vulnerability identification
https://mattermost.com/security-updates
https://mattermost.com/security-updates