CVE-2018-11736 in Pluck
Summary
by MITRE
An issue was discovered in Pluck before 4.7.7-dev2. /data/inc/images.php allows remote attackers to upload and execute arbitrary PHP code by using the image/jpeg content type for a .htaccess file.
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Analysis
by VulDB Data Team • 12/09/2025
The vulnerability identified as CVE-2018-11736 represents a critical security flaw in the Pluck content management system prior to version 4.7.7-dev2. This issue stems from improper input validation and file handling mechanisms within the application's image upload functionality. The vulnerability specifically affects the /data/inc/images.php script which processes file uploads without adequate sanitization of file extensions or content types, creating an avenue for malicious code execution.
The technical exploitation of this vulnerability relies on a sophisticated attack vector involving the manipulation of file content types during upload operations. Attackers can leverage the image/jpeg content type to disguise malicious .htaccess files as legitimate image uploads. This technique exploits the application's trust in content type headers and fails to validate the actual file content against expected formats. The .htaccess file, when uploaded with a disguised content type, can contain malicious PHP code that executes within the web server context, effectively granting attackers remote code execution capabilities.
This vulnerability aligns with CWE-434 which describes "Unrestricted Upload of File with Dangerous Type" and represents a classic case of insecure file upload handling. The operational impact of this flaw extends beyond simple code execution to encompass full system compromise potential. Attackers can leverage this vulnerability to establish persistent backdoors, exfiltrate sensitive data, or deploy additional malware within the compromised environment. The attack requires minimal privileges and can be executed remotely, making it particularly dangerous for web applications hosting sensitive information.
The security implications of CVE-2018-11736 align with several ATT&CK framework techniques including T1059.007 for command and scripting interpreter and T1566 for credential access through social engineering. Organizations running affected versions of Pluck face significant risk of unauthorized access and data breaches. The vulnerability demonstrates the critical importance of proper file validation, content type verification, and secure file handling practices in web applications. The flaw also reflects poor defense-in-depth strategies where multiple layers of security controls fail to prevent malicious file uploads.
Mitigation strategies for this vulnerability require immediate patching of affected systems to version 4.7.7-dev2 or later. Organizations should implement comprehensive file upload restrictions including strict file extension validation, content type verification, and removal of executable permissions from upload directories. Additional protective measures include implementing web application firewalls, conducting regular security audits, and establishing proper access controls. The vulnerability serves as a reminder of the critical need for secure coding practices and regular security assessments to prevent similar flaws in application development processes.