CVE-2025-11935
📋 TL;DR
This TLS 1.3 vulnerability allows malicious servers to bypass perfect forward secrecy (PFS) requirements when using pre-shared keys (PSK). Clients may unknowingly establish connections without PFS, reducing cryptographic security. This affects TLS 1.3 implementations that support PSK with DHE key exchange.
💻 Affected Systems
- wolfSSL
📦 What is this software?
Wolfssl by Wolfssl
⚠️ Risk & Real-World Impact
Worst Case
Attackers who compromise a server's PSK could decrypt past and future communications from clients that connected without PFS, potentially exposing sensitive data.
Likely Case
Reduced cryptographic security where connections that should have PFS don't, making them vulnerable to future decryption if PSK is compromised.
If Mitigated
With proper controls, the risk is limited to specific TLS 1.3 PSK configurations, and many implementations may not be affected.
🎯 Exploit Status
Exploitation requires server-side control or compromise to manipulate TLS handshake.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: wolfSSL version with PR #9112 integrated
Vendor Advisory: https://github.com/wolfSSL/wolfssl/pull/9112
Restart Required: Yes
Instructions:
1. Update wolfSSL to version containing PR #9112 fix. 2. Recompile applications using wolfSSL. 3. Restart affected services.
🔧 Temporary Workarounds
Disable TLS 1.3 PSK
allDisable pre-shared key support in TLS 1.3 configurations
Configure wolfSSL with --disable-psk or equivalent build option
Require PFS for all connections
allEnforce perfect forward secrecy as mandatory in TLS configuration
Set appropriate TLS context options to require PFS
🧯 If You Can't Patch
- Monitor for unusual TLS handshake patterns indicating PFS bypass attempts
- Implement network segmentation to limit exposure of vulnerable systems
🔍 How to Verify
Check if Vulnerable:
Check wolfSSL version and verify if PR #9112 is included in the codebaseCheck Version:
wolfSSL_version() function call or check library version in buildVerify Fix Applied:
Test TLS 1.3 PSK connections to confirm PFS is properly enforced📡 Detection & Monitoring
Log Indicators:
- TLS handshake failures or warnings related to PSK/PFS negotiation
Network Indicators:
- TLS 1.3 connections with PSK but without DHE key exchange completion
SIEM Query:
TLS handshake events where psk_dhe_ke is present but key_share extension is missing