CVE-2026-15282 in Instant Appointment Plugin
Summary
by MITRE • 07/10/2026
The Instant Appointment plugin for WordPress is vulnerable to arbitrary file uploads due to missing file type validation in the 'insapp_upload_image_as_attachment' function in all versions up to, and including, 1.2. This makes it possible for unauthenticated attackers to upload arbitrary files on the affected site's server which may make remote code execution possible.
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Analysis
by VulDB Data Team • 07/10/2026
The Instant Appointment plugin for WordPress presents a critical security vulnerability that stems from inadequate input validation mechanisms within its file upload functionality. This flaw exists in the 'insapp_upload_image_as_attachment' function and affects all versions up to and including 1.2, creating an exploitable pathway for unauthenticated attackers to compromise affected WordPress installations. The vulnerability's severity is amplified by the absence of proper file type validation checks that should normally prevent malicious files from being uploaded to the server.
The technical implementation of this vulnerability allows attackers to bypass normal security controls through a straightforward exploitation vector. When users attempt to upload files through the plugin's interface, the system fails to verify the actual file content against expected formats, instead relying on potentially manipulated file extensions. This missing validation creates a condition where attackers can upload malicious files with extensions that appear legitimate but contain harmful code. The vulnerability aligns with CWE-434 which specifically addresses insecure upload of executable files, and represents a classic example of insufficient input sanitization in web applications.
The operational impact of this vulnerability extends beyond simple unauthorized file uploads to potentially enable complete system compromise through remote code execution capabilities. Attackers who successfully exploit this vulnerability can upload web shells or other malicious executables that persist on the server and provide ongoing access to compromised systems. This represents a significant threat to WordPress site administrators who may not immediately detect the presence of malicious files within their plugin directories. The vulnerability creates a persistent backdoor that could allow attackers to exfiltrate sensitive data, modify website content, or use the compromised server for further attacks against other systems.
Mitigation strategies for this vulnerability should prioritize immediate patching of the affected plugin to versions that implement proper file type validation and content verification mechanisms. System administrators must ensure that all WordPress installations maintain current plugin versions and regularly monitor for security updates. Additional protective measures include implementing web application firewalls that can detect and block suspicious file upload attempts, restricting file upload permissions at the server level, and establishing monitoring systems that can identify unauthorized file modifications. The vulnerability's exploitation aligns with ATT&CK technique T1505.003 which covers untrusted search path modifications and malicious file uploads, emphasizing the need for comprehensive defensive measures including proper access controls and regular security audits to prevent successful exploitation attempts.