CVE-2018-25247 Overview
CVE-2018-25247 is a Cross-Site Scripting (XSS) vulnerability affecting MyBB Like Plugin version 3.0.0. This vulnerability allows attackers to inject malicious scripts by creating posts or threads with unvalidated subject content. Attackers can craft post subjects containing script tags that execute when other users view the attacker's profile, where liked posts are displayed without proper sanitization.
Critical Impact
Attackers can execute arbitrary JavaScript in victims' browsers when viewing user profiles, potentially leading to session hijacking, credential theft, or unauthorized actions performed on behalf of authenticated users.
Affected Products
- MyBB Like Plugin 3.0.0
- MyBB forums with the Like Plugin installed
Discovery Timeline
- 2026-04-04 - CVE CVE-2018-25247 published to NVD
- 2026-04-07 - Last updated in NVD database
Technical Details for CVE-2018-25247
Vulnerability Analysis
This stored XSS vulnerability exists in the MyBB Like Plugin's handling of post and thread subjects. When a user creates a post or thread, the subject field is not properly sanitized before being stored in the database. The vulnerability is triggered when other users view the attacker's profile page, which displays a list of posts that the user has liked. The liked posts are rendered with their original subject lines, but the plugin fails to escape or sanitize HTML and JavaScript content within these subjects.
The vulnerability is classified under CWE-79 (Improper Neutralization of Input During Web Page Generation), which covers cross-site scripting issues. Since the malicious payload is stored in the database and executed whenever users view the affected profile page, this represents a persistent (stored) XSS attack vector with potential for widespread impact across forum users.
Root Cause
The root cause of this vulnerability is insufficient input validation and output encoding in the MyBB Like Plugin. When displaying liked posts on user profile pages, the plugin directly renders post subjects without applying proper HTML entity encoding or sanitization. This allows script tags and other malicious HTML elements to be interpreted and executed by the victim's browser rather than being displayed as plain text.
Attack Vector
The attack vector is network-based and requires user interaction. An attacker must first create an account on the target MyBB forum and craft a post or thread with a malicious subject containing JavaScript code. When other users navigate to the attacker's profile page and the liked posts section renders the malicious subject, the embedded script executes in the context of the victim's browser session. This can enable session cookie theft, keylogging, phishing attacks, or performing actions as the authenticated victim.
The vulnerability mechanism exploits the lack of output encoding in the profile display functionality. When liked posts are retrieved and displayed, the subject field content passes directly to the DOM without sanitization, allowing embedded <script> tags or event handlers to execute. For technical details and proof-of-concept information, refer to the Exploit-DB #45179 entry.
Detection Methods for CVE-2018-25247
Indicators of Compromise
- Presence of HTML tags or JavaScript in post/thread subjects within the database
- Unusual script execution or browser behavior when viewing user profile pages
- Reports from users of unexpected pop-ups or redirects when browsing the forum
- Web server logs showing requests with encoded script payloads in subject parameters
Detection Strategies
- Implement Web Application Firewall (WAF) rules to detect and block XSS patterns in form submissions
- Review database records for posts and threads containing suspicious HTML or script content
- Deploy browser-based XSS detection tools to identify reflected or stored script execution
- Monitor for anomalous JavaScript execution on profile pages using Content Security Policy (CSP) violation reports
Monitoring Recommendations
- Enable and review CSP violation reports to detect unauthorized script execution attempts
- Implement logging for profile page access combined with anomaly detection for unusual user behavior
- Regularly audit post and thread subjects for HTML content that should not be present
- Monitor for session hijacking indicators such as multiple concurrent sessions from different geographic locations
How to Mitigate CVE-2018-25247
Immediate Actions Required
- Disable the MyBB Like Plugin until a patched version is available and applied
- Audit existing posts and threads for malicious content in subject fields
- Implement a Web Application Firewall with XSS protection rules
- Review user accounts for signs of compromise due to potential session hijacking
Patch Information
Administrators should check the MyBB Plugin Mod page for updated versions of the Like Plugin that address this vulnerability. If no patch is available, consider disabling the plugin or implementing custom sanitization. Additional technical information is available from the VulnCheck MyBB XSS Advisory.
Workarounds
- Disable the Like Plugin's profile display functionality if possible through plugin configuration
- Implement server-side input validation to strip HTML tags from post and thread subjects
- Deploy Content Security Policy headers to restrict inline script execution and mitigate XSS impact
- Consider implementing a custom template modification to apply htmlspecialchars() encoding to subject output
# Example CSP header configuration for Apache
# Add to .htaccess or server configuration
Header set Content-Security-Policy "default-src 'self'; script-src 'self'; style-src 'self' 'unsafe-inline'"
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
