CVE-2026-22880
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Mattermost Mobile Apps SSO Authentication Origin Validation Flaw

Publication date: 2026-05-21

Last updated on: 2026-05-21

Assigner: Mattermost, Inc.

Description
Mattermost Mobile Apps versions <=2.37 11.4 2.0.37 11.0.4 11.1.3 11.3.2 10.11.11.0 fail to properly validate the SSO authentication callback origin which allows an attacker controlling a malicious Mattermost server to steal user credentials for a legitimate Mattermost server via relaying the SSO code exchange flow through the mobile application. Mattermost Advisory ID: MMSA-2025-00564
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Meta Information
Published
2026-05-21
Last Modified
2026-05-21
Generated
2026-06-10
AI Q&A
2026-05-21
EPSS Evaluated
2026-06-09
NVD
CVE-2026-22880
EUVD
EUVD-2026-31250
Affected Vendors & Products
Showing 1 associated CPE
Vendor Product Version / Range
mattermost mobile_apps to 2.37 (inc)
Helpful Resources
Exploitability
CWE
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KEV
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CWE ID Description
CWE-352 The web application does not, or cannot, sufficiently verify whether a request was intentionally provided by the user who sent the request, which could have originated from an unauthorized actor.
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Executive Summary

This vulnerability affects Mattermost Mobile Apps versions up to 2.37, 11.4, 2.0.37, 11.0.4, 11.1.3, 11.3.2, and 10.11.11.0. The issue is that these versions fail to properly validate the Single Sign-On (SSO) authentication callback origin.

Because of this improper validation, an attacker who controls a malicious Mattermost server can steal user credentials for a legitimate Mattermost server. This is done by relaying the SSO code exchange flow through the mobile application.

Impact Analysis

The vulnerability allows an attacker to steal user credentials for a legitimate Mattermost server by exploiting the mobile app's failure to validate the SSO authentication callback origin.

This can lead to unauthorized access to user accounts, potentially compromising sensitive information and communications within the Mattermost environment.

Mitigation Strategies

To mitigate this vulnerability, you should update your Mattermost Mobile Apps to a version later than those affected (versions > 2.37, 11.4, 2.0.37, 11.0.4, 11.1.3, 11.3.2, 10.11.11.0) as the issue involves improper validation of the SSO authentication callback origin.

Additionally, stay informed about security updates and patches by regularly checking the Mattermost Security Updates page and subscribing to their Security Bulletin for fix release notifications.

Compliance Impact

The vulnerability allows an attacker controlling a malicious Mattermost server to steal user credentials for a legitimate Mattermost server by exploiting improper validation of the SSO authentication callback origin. This credential theft could lead to unauthorized access to user data.

Such unauthorized access and potential exposure of user credentials may impact compliance with data protection standards and regulations like GDPR and HIPAA, which require safeguarding user authentication data and preventing unauthorized access.

However, the provided information does not explicitly detail the direct compliance implications or specific regulatory impacts of this vulnerability.

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