CVE-2026-3636: Sanitize team member data returned by API

Published May 22, 2026
·
Updated

Mattermost versions 11.6.x <= 11.6.0, 11.5.x <= 11.5.3, 11.4.x <= 11.4.4, 10.11.x <= 10.11.14 fail to sanitize team member data when returned via API to users without elevated permissions which allows a user without permissions to get data about team members roles via invoking various team API endpoints.. Mattermost Advisory ID: MMSA-2026-00626

Affected Software

1 affected component
Mattermost Mattermost=11.6.0, >=11.5.0<=11.5.3, >=11.4.0<=11.4.4, >=10.11.0<=10.11.14

Remediation

Information

Update Mattermost to versions 11.7.0, 11.6.1, 11.5.4, 11.4.5, 10.11.15 or higher.

Event History

May 22, 2026
CVE Published
via MITRE·10:23 AM
Data Sourced
via MITRE·10:23 AM
RemedyDescriptionSeverityWeakness
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Frequently Asked Questions

1

What is the severity of CVE-2026-3636?

CVE-2026-3636 has a medium severity rating of 4.3.

2

How do I fix CVE-2026-3636?

To fix CVE-2026-3636, update Mattermost to versions 11.7.0, 11.6.1, 11.5.4, 11.4.5, or 10.11.15 or higher.

3

What impact does CVE-2026-3636 have?

CVE-2026-3636 allows unauthorized users to access sensitive team member data through API calls.

4

Which versions of Mattermost are affected by CVE-2026-3636?

Mattermost versions 11.6.x up to 11.6.0, 11.5.x up to 11.5.3, 11.4.x up to 11.4.4, and 10.11.x up to 10.11.14 are affected by CVE-2026-3636.

5

What type of vulnerability is CVE-2026-3636?

CVE-2026-3636 is classified as an infoleak vulnerability due to improper sanitization of team member data.

Company

Resources

Contact

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