CVE-2025-11931
📋 TL;DR
An integer underflow vulnerability in wolfSSL's XChaCha20-Poly1305 decryption function allows attackers to cause out-of-bounds memory access when processing maliciously crafted data. This affects applications that directly call the wc_XChaCha20Poly1305_Decrypt() function for custom encryption/decryption operations. TLS connections are not affected as they don't use this specific function.
💻 Affected Systems
- wolfSSL
📦 What is this software?
Wolfssl by Wolfssl
⚠️ Risk & Real-World Impact
Worst Case
Memory corruption leading to remote code execution, denial of service, or information disclosure depending on how the out-of-bounds access is leveraged by an attacker.
Likely Case
Application crash (denial of service) or potential information leakage from adjacent memory regions when processing malicious encrypted data.
If Mitigated
Limited impact if proper input validation and bounds checking are implemented at the application layer before calling the vulnerable function.
🎯 Exploit Status
Exploitation requires the attacker to provide malicious encrypted data to the vulnerable decryption function. No authentication is needed if the function accepts external input.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Version containing fix from PR #9223
Vendor Advisory: https://github.com/wolfSSL/wolfssl/pull/9223
Restart Required: Yes
Instructions:
1. Update wolfSSL to version containing fix from PR #9223. 2. Recompile applications using wolfSSL. 3. Restart affected services.
🔧 Temporary Workarounds
Disable XChaCha20-Poly1305 usage
allAvoid calling wc_XChaCha20Poly1305_Decrypt() function in application code
Input validation wrapper
allImplement application-level validation of input size before calling decryption function
🧯 If You Can't Patch
- Implement strict input validation and bounds checking in application code before calling the vulnerable decryption function
- Monitor for crashes or abnormal behavior in applications using XChaCha20-Poly1305 decryption
🔍 How to Verify
Check if Vulnerable:
Check if application code calls wc_XChaCha20Poly1305_Decrypt() function and uses wolfSSL versions prior to the fixCheck Version:
wolfssl_version() function or check wolfSSL library version in build configurationVerify Fix Applied:
Verify wolfSSL version includes fix from PR #9223 and test decryption functionality with edge cases📡 Detection & Monitoring
Log Indicators:
- Application crashes or segmentation faults when processing encrypted data
- Memory access violation errors in logs
Network Indicators:
- Unusual patterns of encrypted data being sent to services using XChaCha20-Poly1305
SIEM Query:
Search for process crashes or memory violation errors in applications using wolfSSL library