Executive brief
TextPattern CMS, a popular open-source content management system, is vulnerable to a security flaw in its file upload system. An attacker with basic user permissions can upload a malicious file to the server and use it to take full control of the website. This could lead to the theft of sensitive data, website defacement, or the complete shutdown of the service.
Technical details
An authenticated remote code execution (RCE) vulnerability exists in TextPattern CMS 4.8.7 due to unrestricted file uploads (CWE-434). An attacker with low-level authentication can navigate to the 'Files' section of the content area and upload a PHP shell. Because the application does not properly validate or restrict the file types being uploaded to the /textpattern/files/ directory, the attacker can then execute arbitrary system commands by accessing the uploaded file via a web browser and passing commands through GET parameters (e.g., using the PHP system() function). Proof-of-concept exploits are publicly available.
Affected products
- Textpattern TextPattern CMS 4.8.7
Timeline
- 2021-06-14: other: Initial exploit published on Exploit-DB
- 2026-05-10: advisory: Vulnerability published by VulnCheck and NVD