CVE-2025-13821
Sensitive Data Exposure in Mattermost WebSocket Allows Credential Theft
Publication date: 2026-02-16
Last updated on: 2026-02-18
Assigner: Mattermost, Inc.
Description
Description
CVSS Scores
EPSS Scores
| Probability: | |
| Percentile: |
Meta Information
Affected Vendors & Products
| Vendor | Product | Version / Range |
|---|---|---|
| mattermost | mattermost_server | From 10.11.0 (inc) to 10.11.10 (exc) |
| mattermost | mattermost_server | From 11.2.0 (inc) to 11.2.2 (exc) |
| mattermost | mattermost_server | From 11.1.0 (inc) to 11.1.3 (exc) |
Helpful Resources
Exploitability
| CWE ID | Description |
|---|---|
| CWE-200 | The product exposes sensitive information to an actor that is not explicitly authorized to have access to that information. |
Attack-Flow Graph
AI Powered Q&A
Can you explain this vulnerability to me?
This vulnerability affects certain versions of Mattermost (11.1.x up to 11.1.2, 10.11.x up to 10.11.9, and 11.2.x up to 11.2.1) where the software fails to properly sanitize sensitive data in WebSocket messages.
As a result, authenticated users can exploit this flaw to exfiltrate sensitive information such as password hashes and multi-factor authentication (MFA) secrets by using profile nickname updates or email verification events.
How can this vulnerability impact me? :
The vulnerability allows authenticated users to extract sensitive security information like password hashes and MFA secrets.
This can lead to unauthorized access or compromise of user accounts if attackers leverage the stolen credentials or MFA secrets.
Overall, it poses a significant risk to the confidentiality of user credentials and the security of the affected Mattermost deployment.
How does this vulnerability affect compliance with common standards and regulations (like GDPR, HIPAA)?:
I don't know
How can this vulnerability be detected on my network or system? Can you suggest some commands?
I don't know
What immediate steps should I take to mitigate this vulnerability?
I don't know