CVE-2025-30344
📋 TL;DR
This vulnerability allows attackers to determine whether specific usernames exist in OpenSlides systems by measuring response time differences during login attempts. The timing side-channel reveals user existence without authentication, affecting all OpenSlides deployments before version 4.2.5.
💻 Affected Systems
- OpenSlides
📦 What is this software?
Openslides by Openslides
⚠️ Risk & Real-World Impact
Worst Case
Attackers can enumerate all valid usernames, enabling targeted credential stuffing attacks and facilitating social engineering or spear-phishing campaigns against identified users.
Likely Case
Attackers discover valid usernames through automated timing attacks, then attempt password guessing or credential stuffing against those accounts.
If Mitigated
With rate limiting and monitoring, attackers may still discover some usernames but face detection and limited success in credential attacks.
🎯 Exploit Status
Exploitation requires timing measurements but can be automated with simple scripts.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 4.2.5
Vendor Advisory: https://github.com/OpenSlides/OpenSlides/releases/tag/4.2.5
Restart Required: Yes
Instructions:
1. Backup your OpenSlides instance. 2. Update to OpenSlides 4.2.5 or later. 3. Restart the OpenSlides service. 4. Verify the update completed successfully.
🔧 Temporary Workarounds
Implement Rate Limiting
allAdd rate limiting to the /system/auth/login/ endpoint to slow down timing attacks
# Configure rate limiting in your web server or application firewall
Add Random Delay
allIntroduce random delays in login responses to obscure timing differences
# Modify login handler to add random sleep before response
🧯 If You Can't Patch
- Implement network-level rate limiting and monitoring for login attempts
- Deploy a WAF with timing attack protection in front of OpenSlides
🔍 How to Verify
Check if Vulnerable:
Test login endpoint response times with valid vs invalid usernames; consistent timing differences indicate vulnerability.Check Version:
Check OpenSlides version in web interface or via API endpointVerify Fix Applied:
After patching, verify that response times are consistent regardless of username validity.📡 Detection & Monitoring
Log Indicators:
- Multiple failed login attempts for non-existent users
- Unusual patterns of login requests from single IPs
Network Indicators:
- High volume of POST requests to /system/auth/login/
- Requests with varying usernames from same source
SIEM Query:
source_ip=* AND url_path="/system/auth/login/" AND http_method=POST | stats count by source_ip, user_agent