Overview
CVE-2025-12528 identifies a high-severity arbitrary file upload vulnerability found in the Pie Forms for WP plugin for WordPress. Affecting all versions up to and including 1.6, this vulnerability could allow unauthenticated attackers to upload malicious files, potentially leading to remote code execution (RCE) on the affected server. While exploiting this vulnerability requires some degree of predictability in the upload directory, the risk remains significant.
Technical Details
The vulnerability resides within the format_classic function of the plugin’s file upload handling mechanism. Specifically, the validate_classic method checks file extensions but does not adequately prevent the file upload process from proceeding even when invalid extensions are detected. This flaw enables attackers to bypass intended restrictions and upload files with dangerous extensions, such as PHP. The relevant code snippets can be found in the following files:
Exploitation is partially mitigated by the requirement to guess the upload directory, which is a hashed value, and the use of a secure hash for the file name. However, the predictable nature of the hash generation increases the likelihood of successful exploitation.
CVSS Analysis
The Common Vulnerability Scoring System (CVSS) assigns CVE-2025-12528 a score of 8.1, classifying it as HIGH severity. This score reflects the potential for significant impact on confidentiality, integrity, and availability. The vulnerability’s exploitability is considered relatively high due to the ease of triggering the flawed file upload process, even though some hurdles exist in ensuring successful RCE.
Possible Impact
Successful exploitation of this vulnerability could have severe consequences, including:
- Remote Code Execution (RCE): Uploading and executing malicious PHP files could allow an attacker to gain complete control of the WordPress server.
- Website Defacement: Attackers could modify website content, injecting malicious code or replacing existing pages.
- Data Theft: Sensitive data stored on the server, including user credentials and database information, could be compromised.
- Malware Distribution: The compromised website could be used to distribute malware to visitors.
Mitigation or Patch Steps
The primary mitigation is to update the Pie Forms for WP plugin to a version higher than 1.6, if a patched version is available. The developers should implement proper file type validation that prevents the upload of disallowed file types, regardless of extension. If an update is not available, consider temporarily disabling the plugin until a patch is released. Additionally, implementing server-side restrictions on file uploads and monitoring website activity for suspicious file uploads can provide supplementary security measures.
Important: Verify that the plugin version you are updating to specifically addresses CVE-2025-12528.
