CVE-2021-42216
📋 TL;DR
CVE-2021-42216 is a critical cryptographic vulnerability in AnonAddy email forwarding service that allows attackers to bypass email verification and potentially compromise user accounts. The vulnerability affects AnonAddy 0.8.5 and earlier versions, impacting all users of the self-hosted software. Attackers can exploit weak cryptographic implementation to forge verification tokens.
💻 Affected Systems
- AnonAddy
📦 What is this software?
Anonaddy by Anonaddy
⚠️ Risk & Real-World Impact
Worst Case
Complete account takeover, unauthorized access to email forwarding services, and potential exposure of sensitive communications.
Likely Case
Account compromise leading to unauthorized email forwarding, privacy violations, and potential credential theft.
If Mitigated
Limited impact with proper network segmentation and monitoring, but verification bypass remains possible.
🎯 Exploit Status
Exploitation requires understanding of the cryptographic weakness but is technically straightforward.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 0.8.6 and later
Vendor Advisory: https://github.com/anonaddy/anonaddy/security/advisories
Restart Required: Yes
Instructions:
1. Update to AnonAddy 0.8.6 or later. 2. Run 'composer update' to update dependencies. 3. Clear application cache. 4. Restart PHP-FPM/webserver.
🔧 Temporary Workarounds
Disable email verification temporarily
allTemporarily disable email verification feature until patched
Edit VerificationController.php to return early with error
🧯 If You Can't Patch
- Implement network-level restrictions to limit access to verification endpoints
- Enable detailed logging and monitoring for verification attempts
🔍 How to Verify
Check if Vulnerable:
Check if using AnonAddy version 0.8.5 or earlier by examining the composer.json or package versionCheck Version:
grep -r 'version' composer.json || cat vendor/anonaddy/anonaddy/VERSIONVerify Fix Applied:
Verify version is 0.8.6 or later and check that VerificationController.php uses secure cryptographic functions📡 Detection & Monitoring
Log Indicators:
- Unusual verification attempts
- Multiple failed verifications from same IP
- Verification bypass patterns
Network Indicators:
- Abnormal traffic to /email/verify endpoints
- Suspicious verification token patterns
SIEM Query:
source="anonaddy.logs" AND ("verification" OR "verify") AND status="200" AND user_agent="suspicious"🔗 References
- http://anonaddy.com
- https://github.com/anonaddy/anonaddy/blob/0478d9e8d364787f203113544123048a41f022c0/app/Http/Controllers/Auth/VerificationController.php#L67
- https://huntr.dev/bounties/419f4e8a-ee15-4f80-bcbf-5c83513515dd
- http://anonaddy.com
- https://github.com/anonaddy/anonaddy/blob/0478d9e8d364787f203113544123048a41f022c0/app/Http/Controllers/Auth/VerificationController.php#L67
- https://huntr.dev/bounties/419f4e8a-ee15-4f80-bcbf-5c83513515dd
