CVE-2025-45769
📋 TL;DR
CVE-2025-45769 involves weak encryption in php-jwt v6.11.0 due to insufficient key length validation, potentially allowing attackers to forge or tamper with JWT tokens. This affects applications using php-jwt library for authentication/authorization. The vulnerability is disputed as the library expects applications to set proper key lengths.
💻 Affected Systems
- firebase/php-jwt
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Attackers forge valid JWT tokens, gaining unauthorized access to sensitive systems, impersonating users, or escalating privileges.
Likely Case
Authentication bypass in applications with weak key configurations, allowing unauthorized access to protected resources.
If Mitigated
Minimal impact if applications use strong cryptographic keys and proper key length validation.
🎯 Exploit Status
Exploitation requires knowledge of weak key configurations and ability to intercept/modify JWT tokens.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: N/A
Vendor Advisory: https://github.com/firebase/php-jwt/issues/620
Restart Required: No
Instructions:
1. Review the GitHub issue #620 for context. 2. Ensure your application uses strong cryptographic keys (minimum 256-bit for HS256). 3. Implement key length validation in your application code.
🔧 Temporary Workarounds
Enforce Strong Key Validation
allAdd application-level validation to ensure JWT signing keys meet minimum strength requirements
// PHP example: Validate key length before JWT operations
if (strlen($key) < 32) { throw new Exception('Key too weak'); }
🧯 If You Can't Patch
- Implement additional authentication layers (e.g., multi-factor authentication)
- Monitor JWT usage patterns for anomalies and implement rate limiting
🔍 How to Verify
Check if Vulnerable:
Check if using php-jwt v6.11.0 and review application code for weak key usage (keys shorter than 32 bytes for HS256).Check Version:
composer show firebase/php-jwt | grep versionVerify Fix Applied:
Verify application uses keys with sufficient length (≥256-bit) and includes key strength validation.📡 Detection & Monitoring
Log Indicators:
- Multiple failed JWT validations from single source
- JWT tokens with unusually short signatures
Network Indicators:
- Unusual JWT token patterns in authentication requests
SIEM Query:
source="web_logs" AND (message="JWT validation failed" OR message="Invalid signature") | stats count by src_ip🔗 References
- https://gist.github.com/ZupeiNie/83756316c4c24fe97a50176a92608db3
- https://github.com/advisories/GHSA-2x45-7fc3-mxwq
- https://github.com/firebase
- https://github.com/firebase/php-jwt
- https://github.com/firebase/php-jwt/issues/620
- https://github.com/firebase/php-jwt/pull/613
- https://github.com/firebase/php-jwt/releases/tag/v7.0.0
- https://github.com/github/advisory-database/pull/6954
