Full Report
An arbitrary file upload vulnerability in the Chaty Pro plugin has been identified, affecting 18,000 WordPress sites
Analysis Summary
# Vulnerability: Arbitrary File Upload in Chaty Pro WordPress Plugin
## CVE Details
- CVE ID: CVE-2025-26776
- CVSS Score: Not specified in the text (Severity inferred as High due to Remote Code Execution potential)
- CWE: CWE-434 (Unrestricted Upload of File with Dangerous Type) - Inferred from arbitrary file upload vulnerability.
## Affected Systems
- Products: Chaty Pro WordPress Plugin
- Versions: Versions prior to 3.3.4
- Configurations: WordPress sites using the Chaty Pro plugin.
## Vulnerability Description
The vulnerability is an arbitrary file upload flaw existing within the plugin's `chaty_front_form_save_data` function. This issue arises from a lack of proper authorization and nonce checks on user input handling. Although the code intended to use a whitelist for allowed file extensions, this mechanism was not implemented, leaving the system vulnerable. An attacker can upload malicious files (such as PHP files) which, due to filename construction involving the upload time and a random number, can potentially be guessed or brute-forced to gain remote access and achieve full site control if the uploaded file is successfully executed.
## Exploitation
- Status: PoC available (Implied by detailed description suggesting brute-forcing technique)
- Complexity: Medium (Requires knowledge of the upload functionality and timing for brute-forcing filenames)
- Attack Vector: Network
## Impact
- Confidentiality: High (Potential for RCE leads to full data access)
- Integrity: High (Potential for RCE leads to full system modification)
- Availability: High (Potential for RCE leads to site defacement or shutdown)
## Remediation
### Patches
- **Version 3.3.4** or later. The patch replaced the insecure use of `move_uploaded_file()` with `wp_handle_upload()`, implementing proper validation for file extensions and content, and adding stricter security access controls.
### Workarounds
- Update immediately to version 3.3.4.
- **General Guidance for developers (if patching is delayed):**
* Validate both file extensions and content.
* Avoid relying on user-supplied file names.
* Use randomized file names stored securely.
* Restrict executable file uploads.
* Implement proper access controls.
## Detection
- **Indicators of Compromise:** Unexpected or recently uploaded files in WordPress directories, especially PHP files that do not match legitimate plugin content, particularly around the time of known upload attempts.
- **Detection Methods and Tools:** Web Application Firewalls (WAF) configured to block suspicious file uploads or requests targeting upload handlers, and file integrity monitoring (FIM) tools scanning plugin directories.
## References
- Vendor advisory (Implied through PatchStack disclosure): PatchStack Advisory
- Relevant links: cve org/CVERecord?id=CVE-2025-26776