CVE-2015-4455 in Aviary Image Editor Add-on for Gravity Forms Plugin
Summary
by MITRE
Unrestricted file upload vulnerability in includes/upload.php in the Aviary Image Editor Add-on For Gravity Forms plugin 3.0 beta for WordPress allows remote attackers to execute arbitrary code by uploading a file with an executable extension, then accessing it via a direct request to the file in wp-content/uploads/gform_aviary.
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Analysis
by VulDB Data Team • 02/08/2025
The CVE-2015-4455 vulnerability represents a critical unrestricted file upload flaw in the Aviary Image Editor Add-on For Gravity Forms plugin version 3.0 beta for WordPress. This vulnerability resides within the includes/upload.php file and creates a dangerous pathway for remote attackers to execute arbitrary code on affected systems. The flaw specifically allows malicious actors to bypass normal file upload restrictions by uploading files with executable extensions, effectively transforming the WordPress installation into a potential command execution platform.
The technical implementation of this vulnerability stems from inadequate input validation and sanitization within the file upload mechanism. When users upload files through the gravity forms interface, the plugin fails to properly verify file extensions or content types, permitting the upload of potentially malicious files. The vulnerability is particularly dangerous because it allows attackers to upload files with extensions such as .php, .asp, or other executable formats that can be executed directly by the web server. Once uploaded, these files become accessible through the wp-content/uploads/gform_aviary directory structure, providing direct access paths for code execution.
The operational impact of this vulnerability extends beyond simple code execution, as it enables attackers to gain persistent access to compromised WordPress installations. The vulnerability aligns with CWE-434, which specifically addresses unrestricted uploads of files with dangerous types, and represents a classic path for achieving remote code execution through web application vulnerabilities. Attackers can leverage this weakness to deploy web shells, inject malicious scripts, or establish backdoors that maintain access to the compromised system. The attack surface is further expanded because the vulnerability affects a widely used plugin, increasing the potential attack volume against vulnerable installations.
This vulnerability directly maps to several ATT&CK techniques including T1190 for exploit public-facing application and T1059 for command and script execution. The attack chain typically involves uploading a malicious payload, then accessing it through direct web requests to the uploaded file location. The affected plugin's architecture creates a predictable upload path that attackers can easily identify and exploit, making this vulnerability particularly dangerous in automated attack scenarios. Organizations running vulnerable versions of the plugin face significant risk of full system compromise, data theft, and potential use as a launching point for further attacks within their network infrastructure.
Mitigation strategies for CVE-2015-4455 should focus on immediate plugin updates to versions that address the unrestricted file upload vulnerability. Administrators must implement proper file type validation and content inspection mechanisms, ensuring that uploaded files are scanned for malicious content before being stored on the server. The recommended approach includes implementing strict file extension filtering, using random naming conventions for uploaded files, and ensuring that uploaded files are not directly executable by the web server. Additionally, proper access controls should be implemented to prevent direct access to upload directories, and network segmentation should be considered to limit the potential impact of successful exploitation. Regular security audits and vulnerability assessments should be conducted to identify similar weaknesses in other plugins or themes that may provide alternative attack vectors.