CVE-2023-5840
📋 TL;DR
This vulnerability allows attackers to bypass password recovery mechanisms in LinkStack versions prior to 4.2.9, potentially enabling unauthorized account access. It affects all users of vulnerable LinkStack instances where password recovery is enabled. Attackers can exploit weak validation in the password reset process to take over user accounts.
💻 Affected Systems
- LinkStack
📦 What is this software?
Linkstack by Linkstack
⚠️ Risk & Real-World Impact
Worst Case
Complete account takeover of any user, including administrators, leading to data theft, privilege escalation, and potential compromise of the entire LinkStack instance.
Likely Case
Unauthorized access to user accounts, allowing attackers to modify profiles, steal personal information, or use accounts for phishing campaigns.
If Mitigated
Limited impact with proper rate limiting, strong password policies, and monitoring; attackers would need additional information to successfully exploit.
🎯 Exploit Status
Exploitation requires only knowledge of target email/username; no authentication needed. Simple automated tools could be developed.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: v4.2.9
Vendor Advisory: https://github.com/linkstackorg/linkstack/commit/fe7b99eae88f9e4c4cd4b00bab372cbf4b584b16
Restart Required: Yes
Instructions:
1. Backup your LinkStack instance. 2. Update to v4.2.9 via git pull or download. 3. Run database migrations if required. 4. Restart the web server/service.
🔧 Temporary Workarounds
Disable Password Recovery
allTemporarily disable the password recovery functionality to prevent exploitation.
Modify configuration to disable password reset endpoints or remove the feature from the UI.
Implement Rate Limiting
allAdd strict rate limiting to password reset endpoints to prevent brute-force attacks.
Configure web server (nginx/apache) or application-level rate limiting for /password/reset paths.
🧯 If You Can't Patch
- Implement multi-factor authentication (MFA) for all user accounts to add an additional layer of protection.
- Monitor logs for unusual password reset attempts and implement alerting for suspicious patterns.
🔍 How to Verify
Check if Vulnerable:
Check if LinkStack version is below 4.2.9 by examining the version file or admin panel.Check Version:
Check the version in the admin panel or look for version files in the installation directory.Verify Fix Applied:
After updating to v4.2.9, test the password reset functionality to ensure it requires proper validation.📡 Detection & Monitoring
Log Indicators:
- Multiple failed password reset attempts from single IP
- Password reset requests for non-existent users
- Unusual patterns in password reset logs
Network Indicators:
- High volume of POST requests to /password/reset endpoints
- Requests with malformed or suspicious parameters
SIEM Query:
source="linkstack_logs" AND (url_path="/password/reset" OR event="password_reset") | stats count by src_ip, user🔗 References
- https://github.com/linkstackorg/linkstack/commit/fe7b99eae88f9e4c4cd4b00bab372cbf4b584b16
- https://huntr.com/bounties/8042d8c3-650e-4c0d-9146-d9ccf6082b30
- https://github.com/linkstackorg/linkstack/commit/fe7b99eae88f9e4c4cd4b00bab372cbf4b584b16
- https://huntr.com/bounties/8042d8c3-650e-4c0d-9146-d9ccf6082b30
