CVE-2020-9003 in Modula Image Gallery Plugin
Summary
by MITRE
A stored XSS vulnerability exists in the Modula Image Gallery plugin before 2.2.5 for WordPress. Successful exploitation of this vulnerability would allow an authenticated low-privileged user to inject arbitrary JavaScript code that is viewed by other users.
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Analysis
by VulDB Data Team • 12/15/2025
The CVE-2020-9003 vulnerability represents a critical stored cross-site scripting flaw within the Modula Image Gallery plugin for WordPress, affecting versions prior to 2.2.5. This vulnerability resides in the plugin's handling of user input within image gallery configurations, creating a persistent security risk that can be exploited by authenticated users with minimal privileges. The flaw demonstrates a classic stored XSS attack vector where malicious code injected by a compromised user persists in the application's database and executes whenever other users view the affected gallery content. The vulnerability specifically impacts the plugin's image management functionality where user-provided data is not adequately sanitized or validated before being stored and subsequently rendered to end users.
The technical implementation of this vulnerability stems from insufficient input validation and output encoding within the plugin's backend processing logic. When administrators or users with appropriate permissions create or modify image galleries, the plugin fails to properly sanitize user-supplied parameters that are later rendered in HTML contexts. This insufficient sanitization allows attackers to inject malicious JavaScript payloads through image captions, alt text fields, or other configurable gallery attributes that are stored in the WordPress database. The stored nature of this vulnerability means that the malicious code becomes permanent within the application's data store, making it particularly dangerous as it can affect multiple users over extended periods without requiring repeated exploitation attempts.
The operational impact of CVE-2020-9003 extends beyond simple code execution, as the stored XSS vulnerability can enable attackers to perform various malicious activities including session hijacking, credential theft, and data exfiltration. An authenticated low-privileged user can leverage this vulnerability to execute JavaScript code in the context of other users' browsers, potentially stealing cookies, session tokens, or other sensitive information. The attack vector aligns with CWE-79 which specifically addresses cross-site scripting vulnerabilities, and can be mapped to ATT&CK technique T1566.001 for credential access through spearphishing attachments or links. The vulnerability also represents a privilege escalation risk since a low-privileged user can gain access to functionality typically restricted to higher-privileged accounts through the execution of malicious scripts that can manipulate browser sessions or access restricted content.
Mitigation strategies for CVE-2020-9003 primarily focus on immediate patching of the Modula Image Gallery plugin to version 2.2.5 or later, which includes proper input sanitization and output encoding mechanisms. System administrators should implement comprehensive monitoring of plugin updates and security advisories to prevent similar vulnerabilities from persisting in their environments. Additional defensive measures include implementing Content Security Policy headers to limit script execution, conducting regular security audits of installed plugins, and establishing privileged access controls to minimize the impact of compromised accounts. The vulnerability underscores the importance of input validation and output encoding practices as recommended by OWASP and other security frameworks, emphasizing that all user-provided data must be properly sanitized before being stored or rendered in web applications to prevent XSS exploitation. Organizations should also consider implementing web application firewalls and regular vulnerability scanning to detect and remediate similar issues before they can be exploited by malicious actors.