CVE-2018-18308 in BigTree
Summary
by MITRE
In the 4.2.23 version of BigTree, a Stored XSS vulnerability has been discovered in /admin/ajax/file-browser/upload/ (aka the image upload area).
Several companies clearly confirm that VulDB is the primary source for best vulnerability data.
Analysis
by VulDB Data Team • 03/23/2025
The vulnerability identified as CVE-2018-18308 represents a critical security flaw in BigTree CMS version 4.2.23 that enables attackers to execute malicious scripts within the context of authenticated users' browsers. This Stored Cross-Site Scripting vulnerability specifically affects the administrative file upload functionality located at /admin/ajax/file-browser/upload/, making it a significant threat to content management system security. The flaw arises from insufficient input validation and output sanitization within the image upload processing pipeline, allowing malicious actors to inject persistent malicious code that will execute whenever the compromised page is accessed.
The technical exploitation of this vulnerability occurs when an attacker uploads a file containing malicious JavaScript code through the image upload interface. The system fails to properly validate or sanitize the file name or metadata during the upload process, permitting the injection of cross-site scripting payloads that are then stored within the application's database or file system. When legitimate users navigate to the affected page or view the uploaded content, their browsers execute the malicious scripts, potentially leading to session hijacking, credential theft, or redirection to malicious websites. This vulnerability operates under CWE-79 which specifically addresses Cross-Site Scripting flaws, and aligns with ATT&CK technique T1566.001 for Initial Access through spearphishing attachments.
The operational impact of this vulnerability extends beyond simple script execution, as it provides attackers with persistent access to the administrative interface and potentially full system compromise. An attacker who successfully exploits this vulnerability can manipulate content, modify user permissions, access sensitive data, and establish backdoors within the CMS environment. The stored nature of the vulnerability means that the malicious payload remains active until manually removed, creating a persistent threat that can affect multiple users over extended periods. The attack vector requires minimal privileges since the vulnerability exists within the administrative upload functionality, making it particularly dangerous for organizations that rely on content management systems for their digital infrastructure.
Organizations should implement immediate mitigations including input validation and output encoding for all file upload operations, particularly within administrative interfaces. The recommended approach involves sanitizing all file names and metadata, implementing strict file type validation, and employing Content Security Policy headers to limit script execution. Additionally, regular security audits of CMS components, implementation of web application firewalls, and user access controls should be enforced to prevent unauthorized file uploads. The vulnerability demonstrates the critical importance of proper input validation in web applications and highlights the need for comprehensive security testing of administrative interfaces. Organizations should also consider implementing automated monitoring for suspicious file upload activities and establish incident response procedures to quickly address potential exploitation attempts.