Mattermost Plugins up to 1.1.5 Filename path traversal

Summaryinfo

A vulnerability marked as critical has been reported in Mattermost Plugins up to 1.1.5. The affected element is an unknown function of the component Filename Handler. Performing a manipulation results in path traversal. This vulnerability is known as CVE-2026-6957. Remote exploitation of the attack is possible. No exploit is available.

Detailsinfo

A vulnerability was found in Mattermost Plugins up to 1.1.5. It has been classified as critical. This affects an unknown code of the component Filename Handler. The manipulation with an unknown input leads to a path traversal vulnerability. CWE is classifying the issue as CWE-22. The product uses external input to construct a pathname that is intended to identify a file or directory that is located underneath a restricted parent directory, but the product does not properly neutralize special elements within the pathname that can cause the pathname to resolve to a location that is outside of the restricted directory. This is going to have an impact on confidentiality, integrity, and availability. The summary by CVE is:

Mattermost Plugins versions <=1.1.5 fail to sanitize filenames received from federated peers before using them to construct export destination paths, which allows an administrator of a remote federated Mattermost server to write files to arbitrary locations within the target server's filestore via a malicious filename delivered through the shared-channel attachment sync protocol. Mattermost Advisory ID: MMSA-2026-00659

The weakness was published by Hassan Mohammed. The advisory is shared at mattermost.com. This vulnerability is uniquely identified as CVE-2026-6957 since 04/24/2026. The exploitability is told to be difficult. It is possible to initiate the attack remotely. The exploitation requires an enhanced level of successful authentication. Neither technical details nor an exploit are publicly available. The price for an exploit might be around USD $0-$5k at the moment (estimation calculated on 05/27/2026). MITRE ATT&CK project uses the attack technique T1006 for this issue.

There is no information about possible countermeasures known. It may be suggested to replace the affected object with an alternative product.

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Productinfo

Type

• Groupware Software

Vendor

• Mattermost

Name

• Plugins

Version

• 1.1.0
• 1.1.1
• 1.1.2
• 1.1.3
• 1.1.4
• 1.1.5

License

• open-source

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CPE 2.2info

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