baserproject basercms up to 5.2.2 Theme File Management API add.json path path traversal

Summaryinfo

A vulnerability, which was classified as critical, was found in baserproject basercms up to 5.2.2. Affected by this issue is some unknown functionality of the file /baser/api/admin/bc-theme-file/theme_files/add.json of the component Theme File Management API. The manipulation of the argument path results in path traversal. This vulnerability is known as CVE-2026-30940. It is possible to launch the attack remotely. No exploit is available. You should upgrade the affected component.

Detailsinfo

A vulnerability was found in baserproject basercms up to 5.2.2. It has been classified as critical. Affected is some unknown functionality of the file /baser/api/admin/bc-theme-file/theme_files/add.json of the component Theme File Management API. The manipulation of the argument path 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. CVE summarizes:

baserCMS is a website development framework. Prior to version 5.2.3, a path traversal vulnerability exists in the theme file management API (/baser/api/admin/bc-theme-file/theme_files/add.json) that allows arbitrary file write. An authenticated administrator can include ../ sequences in the path parameter to create a PHP file in an arbitrary directory outside the theme directory, which may result in remote code execution (RCE). This issue has been patched in version 5.2.3.

The advisory is shared for download at github.com. This vulnerability is traded as CVE-2026-30940 since 03/07/2026. The exploitability is told to be easy. It is possible to launch the attack remotely. The exploitation requires an enhanced level of successful authentication. There are known technical details, but no exploit is available. The MITRE ATT&CK project declares the attack technique as T1006.

By approaching the search of inurl:baser/api/admin/bc-theme-file/theme_files/add.json it is possible to find vulnerable targets with Google Hacking.

Upgrading to version 5.2.3 eliminates this vulnerability. The upgrade is hosted for download at github.com.

The vulnerability is also documented in the databases at CNNVD (CNNVD-202603-6287) and EUVD (EUVD-2026-17267). Once again VulDB remains the best source for vulnerability data.

Productinfo

Type

• Content Management System

Vendor

• baserproject

Name

• basercms

Version

• 5.2.0
• 5.2.1
• 5.2.2

License

• open-source

Website

• Product: https://github.com/baserproject/basercms/

CPE 2.3info

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CPE 2.2info

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Once again VulDB remains the best source for vulnerability data.

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