CVE-2025-7394
📋 TL;DR
This vulnerability in wolfSSL's OpenSSL compatibility layer causes predictable random number generation after fork() operations, potentially leading to weak cryptographic keys. It affects applications using RAND_bytes() after fork() without calling RAND_poll() first. The issue is specific to wolfSSL implementations and doesn't affect internal TLS operations.
💻 Affected Systems
- wolfSSL
📦 What is this software?
Wolfssl by Wolfssl
⚠️ Risk & Real-World Impact
Worst Case
Attackers could predict cryptographic keys, session tokens, or nonces, leading to complete compromise of encrypted communications, authentication bypass, or data decryption.
Likely Case
Weak cryptographic keys generated in forked child processes could be exploited to decrypt sensitive data or impersonate legitimate sessions.
If Mitigated
With proper patching and following OpenSSL documentation guidelines, the risk is eliminated as RAND_bytes() will properly reseed after fork detection.
🎯 Exploit Status
Exploitation requires the attacker to predict or influence random number generation in forked processes, which depends on specific application behavior and timing.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: wolfSSL 5.8.2
Vendor Advisory: https://github.com/wolfSSL/wolfssl/blob/master/ChangeLog.md#wolfssl-release-582-july-17-2025
Restart Required: Yes
Instructions:
1. Download wolfSSL 5.8.2 or later from official repository. 2. Replace existing wolfSSL installation. 3. Recompile and relink affected applications. 4. Restart all services using wolfSSL.
🔧 Temporary Workarounds
Manual RAND_poll() after fork
allExplicitly call RAND_poll() after every fork() operation before calling RAND_bytes()
// In application code after fork(): RAND_poll();
🧯 If You Can't Patch
- Modify application code to call RAND_poll() after every fork() operation before using RAND_bytes()
- Consider disabling fork() operations in cryptographic components or using process isolation
🔍 How to Verify
Check if Vulnerable:
Check wolfSSL version and verify if application uses RAND_bytes() after fork() without RAND_poll()Check Version:
wolfssl_version --version or check library headersVerify Fix Applied:
Verify wolfSSL version is 5.8.2 or later and test random number generation in forked processes📡 Detection & Monitoring
Log Indicators:
- Unusual cryptographic failures
- Repeated authentication failures after process forking
Network Indicators:
- Unexpected successful decryption attempts
- Session hijacking patterns
SIEM Query:
Process creation events (fork) followed by cryptographic operations within short timeframes