CVE-2023-34103
📋 TL;DR
This CVE describes a stored Cross-Site Scripting (XSS) vulnerability in the Avo Ruby on Rails admin panel framework. Attackers with form edit privileges can inject malicious scripts that execute when other users view the affected content. All Avo users running vulnerable versions are affected.
💻 Affected Systems
- Avo Ruby on Rails admin panel framework
📦 What is this software?
Avo by Avohq
Avo by Avohq
⚠️ Risk & Real-World Impact
Worst Case
Attackers with edit privileges can steal admin session cookies, perform actions as authenticated users, or redirect users to malicious sites, potentially leading to full account compromise.
Likely Case
Privileged users with edit access inject malicious scripts that execute when other users view the affected admin pages, potentially stealing session data or performing unauthorized actions.
If Mitigated
With proper Content Security Policy (CSP) headers and access controls, script execution is blocked and impact is limited to users with edit privileges.
🎯 Exploit Status
Exploitation requires authenticated access with edit privileges. The vulnerability is stored XSS, so no specific timing is needed.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Versions containing commit 7891c01e1fba9ca5d7dbccc43d27f385e5d08563
Vendor Advisory: https://github.com/avo-hq/avo/security/advisories/GHSA-5cr9-5jx3-2g39
Restart Required: Yes
Instructions:
1. Update Avo to version containing commit 7891c01e. 2. Restart your Rails application server. 3. Verify the fix by checking the commit hash in your installation.
🔧 Temporary Workarounds
Implement Content Security Policy (CSP)
allConfigure CSP headers to restrict script execution and mitigate XSS impact
Add CSP headers to your Rails application configuration
Restrict Edit Privileges
allLimit form edit access to trusted users only
Review and tighten Avo user role permissions
🧯 If You Can't Patch
- Implement strict Content Security Policy headers with script-src directives
- Review and limit Avo admin panel access to only essential, trusted personnel
🔍 How to Verify
Check if Vulnerable:
Check if your Avo installation includes commit 7891c01e. If not, you are vulnerable.Check Version:
Check your Gemfile.lock for Avo version or run: git log --oneline | grep 7891c01eVerify Fix Applied:
Verify that commit 7891c01e is present in your Avo installation and test that HTML content in Avo fields is properly sanitized.📡 Detection & Monitoring
Log Indicators:
- Unusual HTML/script content in Avo field submissions
- Multiple failed edit attempts from single user
Network Indicators:
- Outbound connections to suspicious domains from admin panel sessions
SIEM Query:
source="avo_logs" AND (message="*<script>*" OR message="*javascript:*")