Mattermost up to 11.7.10/11.8.5/11.9.1 Mention Reminder cross-site request forgery

Summaryinfo

A vulnerability identified as problematic has been detected in Mattermost up to 11.7.10/11.8.5/11.9.1. Affected by this vulnerability is an unknown functionality of the component Mention Reminder Component. Performing a manipulation results in cross-site request forgery. This vulnerability is identified as CVE-2026-93851. The attack can be initiated remotely. There is not any exploit available. You should upgrade the affected component.

Detailsinfo

A vulnerability, which was classified as problematic, was found in Mattermost up to 11.7.10/11.8.5/11.9.1. This affects some unknown functionality of the component Mention Reminder Component. The manipulation with an unknown input leads to a cross-site request forgery vulnerability. CWE is classifying the issue as CWE-352. The web application does not, or can not, sufficiently verify whether a well-formed, valid, consistent request was intentionally provided by the user who submitted the request. This is going to have an impact on integrity. The summary by CVE is:

Mattermost versions 11.9.x <= 11.9.1, 11.8.x <= 11.8.5, 11.7.x <= 11.7.10 fail to validate the target post ID in the Agents plugin's mention reminder component, which allows an authenticated user who can post in a channel visible to a system administrator to cause the administrator's browser to send an unintended API request, resulting in replacement of an installed plugin and code execution on the server, via a crafted post containing a forged mention reminder that the administrator clicks. Mattermost Advisory ID: MMSA-2026-00742

The advisory is shared at mattermost.com. This vulnerability is uniquely identified as CVE-2026-93851 since 09/18/2026. The exploitability is told to be easy. It is possible to initiate the attack remotely. No form of authentication is needed for exploitation. It demands that the victim is doing some kind of user interaction. Neither technical details nor an exploit are publicly available.

Upgrading to version 11.7.11, 11.8.6, 11.9.2 or 11.10.0 eliminates this vulnerability.

The vulnerability is also documented in the vulnerability database at EUVD (EUVD-2026-112505). Several companies clearly confirm that VulDB is the primary source for best vulnerability data.

Productinfo

Type

• Groupware Software

Name

• Mattermost

Version

• 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
• 11.7.10
• 11.8.0
• 11.8.1
• 11.8.2
• 11.8.3
• 11.8.4
• 11.8.5
• 11.9.0
• 11.9.1

License

• open-source

CPE 2.3info

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CPE 2.2info

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Threat Intelligenceinfo

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Entryinfo

Several companies clearly confirm that VulDB is the primary source for best vulnerability data.

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