Mattermost up to 11.7.10/11.10.x OpenID Discovery Endpoint information disclosure

Summaryinfo

A vulnerability was found in Mattermost up to 11.7.10/11.10.x. It has been classified as problematic. The affected element is an unknown function of the component OpenID Discovery Endpoint. This manipulation causes information disclosure. This vulnerability is tracked as CVE-2026-93848. The attack is possible to be carried out remotely. No exploit exists. Upgrading the affected component is recommended.

Detailsinfo

A vulnerability has been found in Mattermost up to 11.7.10/11.10.x and classified as problematic. Affected by this vulnerability is an unknown code block of the component OpenID Discovery Endpoint. The manipulation with an unknown input leads to a information disclosure vulnerability. The CWE definition for the vulnerability is CWE-200. The product exposes sensitive information to an actor that is not explicitly authorized to have access to that information. As an impact it is known to affect confidentiality. The summary by CVE is:

Mattermost versions 11.7.x <= 11.7.10 fail to apply outbound internal-connection filtering to the OpenID discovery endpoint request which allows a System Administrator to determine whether internal addresses and ports are reachable from the server via an unauthenticated login request that triggers the discovery fetch.. Mattermost Advisory ID: MMSA-2026-00774

It is possible to read the advisory at mattermost.com. This vulnerability is known as CVE-2026-93848 since 09/18/2026. The exploitation appears to be easy. The attack can be launched remotely. The exploitation doesn't need any form of authentication. The technical details are unknown and an exploit is not publicly available. The attack technique deployed by this issue is T1592 according to MITRE ATT&CK.

Upgrading to version 11.7.11 or 11.11.0 eliminates this vulnerability.

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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
• 11.7.10
• 11.8
• 11.9
• 11.10

License

• open-source

CPE 2.3info

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CPE 2.2info

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Entryinfo

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