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 prevent rendering of external SVGs on link embeds which allows unauthenticated users to crash the Mattermost webapp and desktop app via creating an issue or PR on GitHub.. Mattermost Advisory ID: MMSA-2026-00595
Attack Parameters
Attack Vector
Network
Can be exploited remotely
Attack Complexity
Low
Easy to exploit
Privileges Required
None
No privileges needed
User Interaction
None
No user interaction needed
Impact Assessment
Confidentiality
None
No data leak
Integrity
None
No data modification
Availability
High
Complete denial of service
CVSS Vector v3.1
Weakness Type (CWE)
Vulnerable Products 4
| Configuration | From (including) | Up to (excluding) |
|---|---|---|
|
Mattermost Mattermost_Server
cpe:2.3:a:mattermost:mattermost_server:*:*:*:*:*:*:*:*
|
10.11.0
|
10.11.12
|
|
Mattermost Mattermost_Server
cpe:2.3:a:mattermost:mattermost_server:*:*:*:*:*:*:*:*
|
11.2.0
|
11.2.4
|
|
Mattermost Mattermost_Server
cpe:2.3:a:mattermost:mattermost_server:*:*:*:*:*:*:*:*
|
11.3.0
|
11.3.2
|
|
Mattermost Mattermost_Server
cpe:2.3:a:mattermost:mattermost_server:*:*:*:*:*:*:*:*
|
11.4.0
|
11.4.1
|