Webmin Usermin up to 2.570 Mailbox mailbox/detachall.cgi attachment path traversal

Summaryinfo

A vulnerability categorized as critical has been discovered in Webmin Usermin up to 2.570. This affects an unknown part of the file mailbox/detachall.cgi of the component Mailbox. Executing a manipulation of the argument attachment can lead to path traversal. This vulnerability is registered as CVE-2026-123621. It is possible to launch the attack remotely. No exploit is available.

Detailsinfo

A vulnerability has been found in Webmin Usermin up to 2.570 and classified as critical. This vulnerability affects an unknown functionality of the file mailbox/detachall.cgi of the component Mailbox. The manipulation of the argument attachment with an unknown input leads to a path traversal vulnerability. The CWE definition for the vulnerability is 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. As an impact it is known to affect confidentiality, integrity, and availability. CVE summarizes:

Usermin through 2.570 contains a path traversal vulnerability in mailbox/detachall.cgi that allows remote unauthenticated attackers to write files outside the temporary directory via unsanitized attachment filenames. Attackers can email attachments with ../ sequences in filenames, and when the recipient downloads all attachments, files like ~/.forward are overwritten, enabling command execution.

The advisory is available at github.com. This vulnerability was named CVE-2026-123621 since 11/06/2026. The exploitation appears to be easy. The attack can be initiated remotely. No form of authentication is required for a successful exploitation. Technical details are known, but there is no available exploit. The structure of the vulnerability defines a possible price range of USD $0-$5k at the moment (estimation calculated on 11/06/2026). This vulnerability is assigned to T1006 by the MITRE ATT&CK project.

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

• Software Management Software

Vendor

• Webmin

Name

• Usermin

Version

• 2.570

License

• open-source

Website

• Product: https://github.com/webmin/usermin/

CPE 2.3info

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CPE 2.2info

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