CVE-2026-30940 baserCMS: Path Traversal in Theme File API Leads to Arbitrary File Write and RCE
An authenticated administrator can exploit path traversal in the theme file API to write arbitrary files, potentially leading to remote code execution.
- Exploited in the wild
- Not known
- Login needed
- An administrator
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-30940?
CVE-2026-30940 is a high-severity path traversal vulnerability in Basercms Basercms, published on 31 Mar 2026. An attacker needs administrator access to exploit it, with no action from the victim.
Official description
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.
Which versions are affected by CVE-2026-30940?
2 open source packages ship an affected version, including baserproject/basercms. It affects 1 product.
| Package | Affected | Fixed in |
|---|---|---|
baserproject/basercms Packagist | All versions | 5.2.3 |
baserproject/basercms Packagist | All versions | 5.2.3 |
Products include Basercms Basercms.
How do I fix CVE-2026-30940?
Upgrade baserproject/basercms to 5.2.3 or later.
Upgrade, and resolve every user-supplied path against an allowed base folder before opening it. More about Path traversal.
Is CVE-2026-30940 being exploited?
There is no known exploitation of CVE-2026-30940 in the wild and no public exploit code.
Other vulnerabilities in Basercms Basercms
- CVE-2023-25654 baserCMS File Uploader Remote Code Execution (RCE) vulnerability
- CVE-2023-25655 baserCMS allows any file to be uploaded
- CVE-2017-10842 baserCMS SQL Injection vulnerability
- CVE-2026-30880 baserCMS: OS command injection vulnerability in installer
- CVE-2026-21861 baserCMS: OS Command Injection Leading to Remote Code Execution (RCE)
Sources
Also known as GHSA-c5c6-37vq-pjcq.