CVE-2023-42270
📋 TL;DR
This CVE describes a Cross-Site Request Forgery (CSRF) vulnerability in Grocy versions up to 4.0.2. Attackers can trick authenticated users into performing unintended actions on the Grocy web application without their knowledge. This affects all Grocy instances with web interfaces accessible to users.
💻 Affected Systems
- Grocy
📦 What is this software?
Grocy by Grocy Project
⚠️ Risk & Real-World Impact
Worst Case
An attacker could perform administrative actions like creating new users, modifying system settings, or deleting critical data by tricking an authenticated administrator into clicking a malicious link.
Likely Case
Attackers could modify inventory data, create unauthorized purchases, or alter user permissions by targeting regular authenticated users.
If Mitigated
With proper CSRF protections and user awareness, the risk is limited to accidental actions by users who click on untrusted links while authenticated.
🎯 Exploit Status
Exploitation requires the victim to be authenticated to Grocy and to interact with a malicious webpage or link.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: > 4.0.2
Vendor Advisory: https://github.com/grocy/grocy/releases
Restart Required: Yes
Instructions:
1. Backup your Grocy installation and database. 2. Download the latest Grocy release from GitHub. 3. Replace the existing installation files with the new version. 4. Restart your web server. 5. Verify the application is functioning correctly.
🔧 Temporary Workarounds
Implement CSRF Tokens Manually
allAdd CSRF protection tokens to all state-changing forms and validate them server-side.
Use SameSite Cookie Attribute
allConfigure session cookies with SameSite=Strict attribute to limit cross-site requests.
Set-Cookie: session=value; SameSite=Strict; Secure; HttpOnly
🧯 If You Can't Patch
- Implement web application firewall (WAF) rules to detect and block CSRF attempts
- Educate users about the risks of clicking unknown links while authenticated to Grocy
🔍 How to Verify
Check if Vulnerable:
Check your Grocy version in the web interface under 'About' or by examining the source code version files.Check Version:
Check the VERSION file in the Grocy installation directory or view the web interface 'About' page.Verify Fix Applied:
After updating, verify the version shows >4.0.2 and test that forms include CSRF tokens in their HTML.📡 Detection & Monitoring
Log Indicators:
- Multiple failed state-changing requests from same IP without proper referrer headers
- Unusual administrative actions from non-admin user accounts
Network Indicators:
- HTTP POST requests to Grocy endpoints without proper referrer headers or CSRF tokens
SIEM Query:
source="grocy_logs" AND (action="create" OR action="modify" OR action="delete") AND referrer NOT CONTAINS "your-grocy-domain"