CVE-2025-61987
📋 TL;DR
This CVE describes a WebSocket origin validation vulnerability in GroupSession products that allows cross-origin WebSocket connections. An attacker can craft a malicious webpage that, when visited by a user, can intercept chat information sent to that user through the vulnerable GroupSession instance. Affected users are those running vulnerable versions of GroupSession Free edition, GroupSession byCloud, or GroupSession ZION.
💻 Affected Systems
- GroupSession Free edition
- GroupSession byCloud
- GroupSession ZION
📦 What is this software?
Groupsession by Groupsession
Groupsession by Groupsession
Groupsession by Groupsession
⚠️ Risk & Real-World Impact
Worst Case
Sensitive chat communications including potentially confidential business discussions, personal information, or authentication tokens could be intercepted by an attacker and used for further attacks.
Likely Case
Attackers create phishing pages that trick users into visiting, then intercept their GroupSession chat data, potentially exposing sensitive conversations.
If Mitigated
With proper network segmentation and user awareness training, the risk is limited to users who visit malicious sites while authenticated to GroupSession.
🎯 Exploit Status
Exploitation requires user interaction (visiting a malicious page) and the user to be authenticated to GroupSession. The technical complexity of creating the exploit is low.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: GroupSession Free edition 5.3.0+, GroupSession byCloud 5.3.3+, GroupSession ZION 5.3.2+
Vendor Advisory: https://groupsession.jp/info/info-news/security20251208
Restart Required: Yes
Instructions:
1. Download the latest version from the official GroupSession website. 2. Backup your current installation and data. 3. Stop the GroupSession service. 4. Install the updated version. 5. Restart the GroupSession service. 6. Verify the version is updated.
🔧 Temporary Workarounds
Web Application Firewall (WAF) Rules
allConfigure WAF rules to block WebSocket connections from unauthorized origins
Content Security Policy (CSP)
allImplement strict CSP headers to restrict WebSocket connections to trusted origins only
🧯 If You Can't Patch
- Implement network segmentation to isolate GroupSession instances from user workstations
- Educate users about phishing risks and safe browsing practices
🔍 How to Verify
Check if Vulnerable:
Check the GroupSession version in the admin panel or configuration files. If version is below the patched versions listed, the system is vulnerable.Check Version:
Check the version in the GroupSession admin interface or configuration files (varies by installation method)Verify Fix Applied:
After patching, verify the version shows 5.3.0+ for Free edition, 5.3.3+ for byCloud, or 5.3.2+ for ZION. Test WebSocket connections from unauthorized origins should be rejected.📡 Detection & Monitoring
Log Indicators:
- WebSocket connection attempts from unexpected origins
- Failed WebSocket handshakes with origin validation errors
Network Indicators:
- WebSocket traffic to GroupSession from non-standard origins
- Increased WebSocket connection attempts
SIEM Query:
websocket AND (origin NOT IN allowed_origins) AND destination_port IN [GroupSession_ports]