Mattermost up to 11.7.9/11.8.5/11.9.1/11.10.0 Team Search privileges management

Summaryinfo

A vulnerability was found in Mattermost up to 11.7.9/11.8.5/11.9.1/11.10.0. It has been rated as problematic. The impacted element is an unknown function of the component Team Search. Performing a manipulation results in privileges management. This vulnerability is reported as CVE-2026-18256. The attack is possible to be carried out remotely. No exploit exists. Upgrading the affected component is advised.

Detailsinfo

A vulnerability was found in Mattermost up to 11.7.9/11.8.5/11.9.1/11.10.0. It has been classified as problematic. This affects an unknown function of the component Team Search. The manipulation with an unknown input leads to a privileges management vulnerability. CWE is classifying the issue as CWE-269. The product does not properly assign, modify, track, or check privileges for an actor, creating an unintended sphere of control for that actor. This is going to have an impact on confidentiality. The summary by CVE is:

Mattermost versions 11.10.x <= 11.10.0, 11.7.x <= 11.7.9, 11.9.x <= 11.9.1, 11.8.x <= 11.8.5 fail to properly restrict private teams from public team search results, which allows an authenticated user without permission to list private teams to disclose the ID, name, and display name of private teams via a modified team search request. Mattermost Advisory ID: MMSA-2026-00748

The advisory is shared at mattermost.com. This vulnerability is uniquely identified as CVE-2026-18256 since 07/29/2026. The exploitability is told to be easy. It is possible to initiate the attack remotely. Neither technical details nor an exploit are publicly available. MITRE ATT&CK project uses the attack technique T1068 for this issue.

Upgrading to version 11.7.10, 11.8.6, 11.9.2, 11.10.1 or 11.11.0 eliminates this vulnerability.

The vulnerability is also documented in the databases at EUVD (EUVD-2026-102749) and CERT Bund (WID-SEC-2026-4009). If you want to get the best quality for vulnerability data then you always have to consider VulDB.

Affected

• Mattermost Mattermost

Productinfo

Type

• Groupware Software

Name

• Mattermost

Version

• 11.0
• 11.1
• 11.2
• 11.3
• 11.4
• 11.5
• 11.6
• 11.7
• 11.7.0
• 11.7.1
• 11.7.2
• 11.7.3
• 11.7.4
• 11.7.5
• 11.7.6
• 11.7.7
• 11.7.8
• 11.7.9
• 11.8
• 11.8.0
• 11.8.1
• 11.8.2
• 11.8.3
• 11.8.4
• 11.8.5
• 11.9
• 11.9.0
• 11.9.1
• 11.10.0

License

• open-source

CPE 2.3info

• 🔒
• 🔒
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CPE 2.2info

• 🔒
• 🔒
• 🔒

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Entryinfo

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