CVE-2026-16548 in The Chat Widget Plugin
Summary
by MITRE • 08/04/2026
The Chat Widget: Floating Customer Support Button for 30+ Channels, Supporting SMS, Calls, and Chat WordPress plugin before 1.8.2 does not validate the type, extension, content, or size of files submitted to its public response endpoint and stores them under the uploads directory, so an unauthenticated user can upload arbitrary files. The original extension is discarded (files are stored under a bare UUID), so this does not yield code execution or stored XSS; impact is bounded to disk consumption and content hosting. The storing path requires the channel's response storage or mail-forwarding to be configured.
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Analysis
by VulDB Data Team • 08/04/2026
The vulnerability in the Chat Widget WordPress plugin affects versions prior to 1.8.2 and represents a significant security flaw that allows unauthenticated users to upload arbitrary files to the target system. This issue stems from insufficient input validation within the plugin's public response endpoint, which processes file uploads without proper sanitization or verification of file attributes. The vulnerability is classified as a weak input validation issue that falls under the broader category of improper input validation CWE-20, and can be mapped to attack techniques such as malicious file upload ATT&CK T1195.001. The plugin's failure to validate file types, extensions, content, or size creates an opportunity for attackers to abuse this functionality.
The technical implementation of this vulnerability occurs through the plugin's response handling mechanism where files are accepted and stored under the WordPress uploads directory. While the system does strip original file extensions and stores files using only a bare UUID, this does not prevent the exploitation as the core issue lies in the lack of proper validation rather than the storage mechanism itself. The storage path requires specific configuration for channel responses or mail-forwarding to be active, which means attackers must first identify a valid endpoint that accepts uploads before they can exploit this weakness. This limitation reduces the attack surface but does not eliminate the risk entirely since any configured channel response system represents a potential vector.
The operational impact of this vulnerability is substantial even though it does not directly enable code execution or stored cross-site scripting. The primary risks include excessive disk space consumption, which can lead to denial of service conditions and resource exhaustion attacks. Additionally, attackers can leverage this capability for content hosting purposes, potentially using the compromised system to store malicious files, phishing materials, or other unwanted content. This vulnerability can be particularly damaging in shared hosting environments or systems with limited storage capacity where unauthorized file uploads can quickly consume available resources and impact legitimate service operations. The bounded nature of the impact does not diminish its severity given that it allows persistent unauthorized access to the file system.
Mitigation strategies for this vulnerability should focus on implementing comprehensive input validation and sanitization measures within the plugin's file upload handling code. The recommended approach includes validating all file attributes including type, extension, content, and size before processing any uploads. Security patches should enforce strict filename restrictions and prevent storage of files without proper validation checks. Organizations should also implement proper access controls to limit which endpoints accept file uploads and ensure that only authenticated users with appropriate privileges can submit content. Additionally, monitoring systems should be deployed to detect unusual file upload patterns or unexpected file types that could indicate exploitation attempts. Regular security audits should validate that all file handling mechanisms within WordPress plugins properly sanitize input and prevent unauthorized file operations. The vulnerability serves as a reminder of the critical importance of proper input validation in web applications and demonstrates how seemingly minor oversights can create significant security risks in content management systems.