CVE-2020-7787
📋 TL;DR
CVE-2020-7787 is an authentication bypass vulnerability in react-adal where specially crafted JWT tokens with empty nonce values can be accepted as authentic due to improper storage validation. This affects all applications using react-adal for Azure Active Directory authentication. Attackers could impersonate legitimate users and gain unauthorized access to protected resources.
💻 Affected Systems
- react-adal
📦 What is this software?
React Adal by React Adal Project
⚠️ Manual Verification Required
This CVE does not have specific version information in our database, so automatic vulnerability detection cannot determine if your system is affected.
Why? The CVE database entry doesn't specify which versions are vulnerable (no version ranges provided by the vendor/NVD).
🔒 Custom verification scripts are available for registered users. Sign up free to download automated test scripts.
- Review the CVE details at NVD
- Check vendor security advisories for your specific version
- Test if the vulnerability is exploitable in your environment
- Consider updating to the latest version as a precaution
⚠️ Risk & Real-World Impact
Worst Case
Complete account takeover allowing attackers to access sensitive data, perform privileged actions, and potentially pivot to other systems.
Likely Case
Unauthorized access to user accounts and application data, leading to data breaches and privilege escalation.
If Mitigated
Limited impact with proper network segmentation, strong monitoring, and multi-factor authentication in place.
🎯 Exploit Status
Exploitation requires the attacker to obtain or craft a JWT token and trigger the authentication callback with empty session parameters.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Versions with the fix from GitHub pull request #115
Vendor Advisory: https://github.com/salvoravida/react-adal/pull/115
Restart Required: Yes
Instructions:
1. Update react-adal to the latest version. 2. Rebuild and redeploy your application. 3. Clear browser storage for affected users. 4. Test authentication flows thoroughly.
🔧 Temporary Workarounds
Implement server-side token validation
allAdd additional server-side validation of JWT tokens beyond what react-adal provides
Use alternative authentication library
allMigrate to a maintained alternative like MSAL.js for Azure AD authentication
🧯 If You Can't Patch
- Implement strict network controls and WAF rules to monitor for authentication anomalies
- Enable enhanced logging and monitoring for authentication events and failed attempts
🔍 How to Verify
Check if Vulnerable:
Check package.json for react-adal version and verify if it's before the fix from PR #115Check Version:
npm list react-adalVerify Fix Applied:
Verify react-adal version is updated and test authentication with various token scenarios📡 Detection & Monitoring
Log Indicators:
- Authentication attempts with empty session parameters
- Unusual authentication patterns from same user
- Multiple failed authentication attempts followed by success
Network Indicators:
- HTTP requests with crafted callback URLs containing empty session parameters
- Unusual JWT token patterns in authentication flows
SIEM Query:
source="application_logs" AND (message CONTAINS "empty session" OR message CONTAINS "authentication bypass" OR message CONTAINS "CVE-2020-7787")