CVE-2025-67163
📋 TL;DR
A stored cross-site scripting (XSS) vulnerability in Simple Machines Forum v2.1.6 allows attackers to inject malicious scripts into the Forum Name parameter, which then executes in victims' browsers when they view forum pages. This affects all users of Simple Machines Forum v2.1.6 who have access to forum administration or can otherwise modify forum names. Attackers can steal session cookies, redirect users, or perform actions on their behalf.
💻 Affected Systems
- Simple Machines Forum
📦 What is this software?
Simple Machines Forum by Simplemachines
⚠️ Risk & Real-World Impact
Worst Case
Attackers gain administrative access by stealing admin session cookies, deface the entire forum, install backdoors, or redirect all users to malicious sites.
Likely Case
Attackers steal user session cookies to hijack accounts, post malicious content, or redirect users to phishing pages.
If Mitigated
Limited to minor defacement or data leakage if proper input validation and output encoding are implemented.
🎯 Exploit Status
Exploitation requires ability to modify forum names, typically through admin panel access. Public proof-of-concept exists in GitHub references.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: v2.1.7 or later
Vendor Advisory: https://github.com/SimpleMachines/SMF/security/advisories/GHSA-p2xm-x9fp-5r7x
Restart Required: No
Instructions:
1. Backup your forum database and files. 2. Download the latest version from Simple Machines Forum website. 3. Replace affected files with patched versions. 4. Clear browser caches and test functionality.
🔧 Temporary Workarounds
Input Validation Filter
allAdd server-side input validation to sanitize forum name inputs before storage.
Modify forum administration scripts to strip HTML/script tags from forum name inputs using functions like strip_tags() or htmlspecialchars()
Output Encoding
allImplement proper output encoding in forum display templates to prevent script execution.
Edit Stats.template.php and other display templates to use htmlspecialchars() or similar encoding when outputting forum names
🧯 If You Can't Patch
- Restrict forum name modification permissions to trusted administrators only
- Implement web application firewall (WAF) rules to block XSS payloads in forum name parameters
🔍 How to Verify
Check if Vulnerable:
Check if running Simple Machines Forum v2.1.6 by examining version in admin panel or source code.Check Version:
Check Admin > Forum Maintenance > Version Information in SMF admin panelVerify Fix Applied:
After patching, attempt to inject basic XSS payload into forum name field and verify it doesn't execute when viewing forum pages.📡 Detection & Monitoring
Log Indicators:
- Unusual forum name modifications containing script tags or JavaScript code
- Multiple failed login attempts followed by forum name changes
Network Indicators:
- HTTP requests with suspicious payloads in forum name parameters
- Unexpected outbound connections from forum pages
SIEM Query:
source="web_logs" AND (uri="*/admin/*" OR uri="*/forum/*") AND (payload CONTAINS "<script>" OR payload CONTAINS "javascript:")🔗 References
- https://github.com/SimpleMachines/SMF
- https://github.com/SimpleMachines/SMF/blob/release-3.0/Themes/default/Stats.template.php#L26
- https://github.com/SimpleMachines/SMF/security/advisories/GHSA-p2xm-x9fp-5r7x
- https://github.com/mbiesiad/vulnerability-research/tree/main/CVE-2025-67163
- https://wiki.simplemachines.org/smf/Installing
