Mattermost up to 10.11.14/11.4.4/11.5.3/11.6.0 Scope authorization

Summaryinfo

A vulnerability classified as critical has been found in Mattermost up to 10.11.14/11.4.4/11.5.3/11.6.0. This impacts an unknown function. The manipulation of the argument Scope leads to authorization. This vulnerability is documented as CVE-2026-28735. The attack can be initiated remotely. There is not any exploit available. It is recommended to upgrade the affected component.

Detailsinfo

A vulnerability, which was classified as critical, has been found in Mattermost up to 10.11.14/11.4.4/11.5.3/11.6.0. This issue affects some unknown processing. The manipulation of the argument scope with an unknown input leads to a authorization vulnerability. Using CWE to declare the problem leads to CWE-863. The product performs an authorization check when an actor attempts to access a resource or perform an action, but it does not correctly perform the check. This allows attackers to bypass intended access restrictions. Impacted is confidentiality, integrity, and availability. The summary by CVE is:

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 validate the OAuth token scope on the callback which allows an authenticated Mattermost user to gain access to private repositories via modifying the scope parameter in the GitHub authorization URL.. Mattermost Advisory ID: MMSA-2026-00628

The weakness was released by eahmed. It is possible to read the advisory at mattermost.com. The identification of this vulnerability is CVE-2026-28735 since 03/10/2026. The exploitation is known to be easy. The attack may be initiated remotely. Technical details of the vulnerability are known, but there is no available exploit.

Upgrading to version 10.11.15, 11.4.5, 11.5.4, 11.6.1 or 11.7.0 eliminates this vulnerability.

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Productinfo

Type

• Groupware Software

Name

• Mattermost

Version

• 10.11.0
• 10.11.1
• 10.11.2
• 10.11.3
• 10.11.4
• 10.11.5
• 10.11.6
• 10.11.7
• 10.11.8
• 10.11.9
• 10.11.10
• 10.11.11
• 10.11.12
• 10.11.13
• 10.11.14
• 11.0
• 11.1
• 11.2
• 11.3
• 11.4
• 11.4.0
• 11.4.1
• 11.4.2
• 11.4.3
• 11.4.4
• 11.5
• 11.5.0
• 11.5.1
• 11.5.2
• 11.5.3
• 11.6.0

License

• open-source

CPE 2.3info

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CPE 2.2info

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Entryinfo

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