CVE-2026-1438
📋 TL;DR
A reflected Cross-Site Scripting (XSS) vulnerability in Graylog Web Interface version 2.2.3 allows attackers to inject and execute arbitrary JavaScript code via specially crafted URLs. This affects Graylog administrators and users who access the web console, potentially leading to session hijacking or limited manipulation of user sessions through the '/system/nodes/' endpoint.
💻 Affected Systems
- Graylog
📦 What is this software?
Graylog by Graylog
⚠️ Risk & Real-World Impact
Worst Case
Attacker steals administrator session cookies, gains full administrative access to Graylog, manipulates log data, or deploys backdoors in the logging infrastructure.
Likely Case
Attacker performs session hijacking of regular users, steals authentication tokens, or performs limited actions within the victim's session context.
If Mitigated
With proper input validation and output encoding, the vulnerability is prevented, and no script execution occurs.
🎯 Exploit Status
Exploitation requires user to click a malicious link; no authentication needed for the vulnerable endpoint.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 2.2.4 or later
Vendor Advisory: https://www.incibe.es/en/incibe-cert/notices/aviso/multiple-vulnerabilities-graylog
Restart Required: Yes
Instructions:
1. Backup Graylog configuration and data. 2. Download and install Graylog version 2.2.4 or later from official sources. 3. Restart Graylog services. 4. Verify the fix by testing the '/system/nodes/' endpoint.
🔧 Temporary Workarounds
Input Validation Filter
allImplement a web application firewall (WAF) or reverse proxy to filter malicious input targeting the '/system/nodes/' endpoint.
Content Security Policy (CSP)
allEnforce a strict CSP header to mitigate XSS impact by restricting script execution sources.
Add to web server config: Content-Security-Policy: default-src 'self'; script-src 'self'
🧯 If You Can't Patch
- Implement strict input validation and output encoding in custom code for the '/system/nodes/' endpoint.
- Restrict access to the Graylog web interface using network segmentation and allow only trusted IP addresses.
🔍 How to Verify
Check if Vulnerable:
Test the '/system/nodes/' endpoint with a simple XSS payload like <script>alert('test')</script> in URL parameters and check if it executes in response.Check Version:
Check Graylog web interface version via the web UI or run: grep version /etc/graylog/server/server.conf (Linux) or equivalent on other OS.Verify Fix Applied:
After patching, retest with the same XSS payload; the script should be properly encoded and not execute.📡 Detection & Monitoring
Log Indicators:
- Unusual requests to '/system/nodes/' with script tags or encoded payloads in Graylog access logs.
- Multiple failed login attempts or session anomalies following suspicious URL accesses.
Network Indicators:
- HTTP requests containing malicious script patterns in query strings targeting Graylog web interface.
SIEM Query:
source="graylog_access.log" AND uri_path="/system/nodes/" AND (query_string="*<script>*" OR query_string="*javascript:*")