CVE-2024-21686
📋 TL;DR
This is a stored cross-site scripting (XSS) vulnerability in Confluence Data Center and Server that allows authenticated attackers to inject malicious HTML/JavaScript into web pages. When victims view these compromised pages, the attacker's code executes in their browsers, potentially stealing session cookies, credentials, or performing unauthorized actions. Affected systems are Confluence Data Center and Server versions 7.13 and later.
💻 Affected Systems
- Confluence Data Center
- Confluence Server
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Attackers steal administrator session cookies, gain full administrative access to Confluence, exfiltrate all stored data, and compromise user accounts through credential theft.
Likely Case
Attackers steal user session cookies to impersonate legitimate users, modify content, or access sensitive information within Confluence.
If Mitigated
With proper input validation and output encoding, malicious payloads are neutralized before reaching user browsers, preventing code execution.
🎯 Exploit Status
Exploitation requires authenticated access to Confluence. The vulnerability is stored XSS, meaning malicious payloads persist until cleaned.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Latest version or specified fixed versions per Atlassian advisory
Vendor Advisory: https://confluence.atlassian.com/pages/viewpage.action?pageId=1417150917
Restart Required: Yes
Instructions:
1. Backup your Confluence instance. 2. Download the latest fixed version from Atlassian's download center. 3. Follow Atlassian's upgrade documentation for your deployment type. 4. Restart Confluence services after upgrade.
🔧 Temporary Workarounds
Input Validation Filter
allImplement web application firewall (WAF) rules or input validation filters to block XSS payloads in user inputs.
Content Security Policy
allImplement strict Content-Security-Policy headers to restrict script execution sources.
🧯 If You Can't Patch
- Restrict user permissions to minimize attack surface - only grant necessary edit/create permissions.
- Implement network segmentation to isolate Confluence from sensitive systems and monitor for suspicious outbound traffic.
🔍 How to Verify
Check if Vulnerable:
Check Confluence version via Administration > General Configuration. If version is 7.13 or higher and not patched, system is vulnerable.Check Version:
Check via Confluence web interface: Administration > General Configuration, or check confluence/WEB-INF/classes/build.properties file.Verify Fix Applied:
Verify Confluence version is updated to a fixed version per Atlassian's advisory. Test XSS payloads in user input fields to ensure they are properly sanitized.📡 Detection & Monitoring
Log Indicators:
- Unusual content creation/modification patterns
- Suspicious user activity from authenticated sessions
- JavaScript or HTML payloads in request logs
Network Indicators:
- Unexpected outbound connections from Confluence server following user interactions
- Data exfiltration patterns
SIEM Query:
source="confluence.log" AND ("<script>" OR "javascript:" OR "onerror=" OR "onload=")