CVE-2026-16985 in Squeeze Plugin
Summary
by MITRE • 08/10/2026
The Squeeze WordPress plugin before 1.7.12 does not validate the file type or extension of the per-size image data written by one of its attachment-update actions, allowing users with the upload_files capability (Author and above) to write an executable PHP file into the uploads directory and achieve remote code execution.
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Analysis
by VulDB Data Team • 08/10/2026
The Squeeze WordPress plugin vulnerability represents a critical security flaw that stems from inadequate input validation within its file handling mechanisms. This weakness exists in versions prior to 1.7.12 and specifically affects the plugin's attachment-update actions where it processes per-size image data. The vulnerability arises because the plugin fails to perform proper file type and extension validation before writing uploaded files to the WordPress uploads directory, creating an exploitable path for privilege escalation and arbitrary code execution.
The technical implementation of this flaw allows users possessing the upload_files capability, which includes roles such as Authors and above, to bypass normal security restrictions. These users can craft malicious PHP files with executable extensions and upload them through the plugin's attachment update functionality. The absence of proper validation means that the system accepts files regardless of their actual content or intended execution context, enabling attackers to place web shells or other malicious code directly into the WordPress uploads directory where they can be executed by the web server.
This vulnerability has significant operational impact as it transforms standard user permissions into a serious security threat. An attacker with Author-level privileges can leverage this flaw to gain full control over the WordPress installation and potentially compromise the entire hosting environment. The remote code execution capability allows for data exfiltration, system reconnaissance, privilege escalation, and persistence mechanisms that can persist even after the initial exploit is executed. The vulnerability affects any WordPress installation running an affected version of the Squeeze plugin, making it particularly dangerous in multi-user environments where authors might have unintended access to critical systems.
The exploitation of this vulnerability aligns with several ATT&CK tactics including privilege escalation and execution through web shell deployment. From a CWE perspective, this represents a classic case of insufficient input validation (CWE-20) combined with insecure file handling practices that enable arbitrary file upload vulnerabilities (CWE-434). The vulnerability also demonstrates poor secure coding practices related to file type verification and access control enforcement. Mitigation strategies should include immediate patching to version 1.7.12 or later, implementing additional file validation layers, restricting upload capabilities for lower-privilege users, and deploying web application firewalls with rules specifically targeting PHP file uploads. Organizations should also conduct thorough security audits of all installed plugins and consider implementing automated monitoring systems that can detect unauthorized file modifications in the uploads directory to prevent exploitation attempts.