Umbraco Umbraco.Forms.Issues up to 16.4.0/17.1.0 on macOS/Linux Export Endpoint fileName path traversal

Summaryinfo

A vulnerability was found in Umbraco Umbraco.Forms.Issues up to 16.4.0/17.1.0 on macOS/Linux. It has been rated as critical. The impacted element is an unknown function of the component Export Endpoint. The manipulation of the argument fileName leads to path traversal. This vulnerability is uniquely identified as CVE-2026-24687. The attack is possible to be carried out remotely. No exploit exists. Upgrading the affected component is advised.

Detailsinfo

A vulnerability was found in Umbraco Umbraco.Forms.Issues up to 16.4.0/17.1.0 on macOS/Linux and classified as critical. This issue affects an unknown function of the component Export Endpoint. The manipulation of the argument fileName with an unknown input leads to a path traversal vulnerability. Using CWE to declare the problem leads to 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. Impacted is confidentiality. The summary by CVE is:

Umbraco Forms is a form builder that integrates with the Umbraco content management system. It's possible for an authenticated backoffice-user to enumerate and traverse paths/files on the systems filesystem and read their contents, on Mac/Linux Umbraco installations using Forms. As Umbraco Cloud runs in a Windows environment, Cloud users aren't affected. This issue affects versions 16 and 17 of Umbraco Forms and is patched in 16.4.1 and 17.1.1. If upgrading is not immediately possible, users can mitigate this vulnerability by configuring a WAF or reverse proxy to block requests containing path traversal sequences (`../`, `..\`) in the `fileName` parameter of the export endpoint, restricting network access to the Umbraco backoffice to trusted IP ranges, and/or blocking the `/umbraco/forms/api/v1/export` endpoint entirely if the export feature is not required. However, upgrading to the patched version is strongly recommended.

It is possible to read the advisory at github.com. The identification of this vulnerability is CVE-2026-24687 since 01/23/2026. 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. The attack technique deployed by this issue is T1006 according to MITRE ATT&CK.

Upgrading to version 16.4.1 or 17.1.1 eliminates this vulnerability.

The vulnerability is also documented in the vulnerability database at EUVD (EUVD-2026-4966). Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.

Productinfo

Vendor

• Umbraco

Name

• Umbraco.Forms.Issues

Version

• 16.0
• 16.1
• 16.2
• 16.3
• 16.4.0
• 17.0
• 17.1.0

Website

• Product: https://github.com/umbraco/Umbraco.Forms.Issues/

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Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.

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