CVE-2025-12889
📋 TL;DR
This TLS 1.2 vulnerability allows clients to use weaker cryptographic digests during certificate authentication than what the server requested, potentially enabling downgrade attacks. It affects systems using wolfSSL library for TLS connections where certificate-based client authentication is required. The vulnerability could allow attackers to bypass intended security controls.
💻 Affected Systems
- wolfSSL
📦 What is this software?
Wolfssl by Wolfssl
⚠️ Risk & Real-World Impact
Worst Case
An attacker could perform a man-in-the-middle attack, downgrade authentication strength, and potentially impersonate legitimate clients or servers in TLS 1.2 connections.
Likely Case
Limited impact in most environments as it requires specific TLS 1.2 configurations with client certificate authentication and an attacker positioned to intercept traffic.
If Mitigated
Minimal impact if TLS 1.3 is used, strong cipher suites are enforced, or proper network segmentation prevents interception.
🎯 Exploit Status
Exploitation requires man-in-the-middle position and specific TLS 1.2 configuration with client certificate authentication.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: wolfSSL 5.7.2
Vendor Advisory: https://github.com/wolfSSL/wolfssl/pull/9395
Restart Required: Yes
Instructions:
1. Download wolfSSL 5.7.2 or later from official sources. 2. Replace vulnerable wolfSSL library. 3. Recompile applications using wolfSSL. 4. Restart affected services.
🔧 Temporary Workarounds
Disable TLS 1.2 client certificate authentication
allRemove client certificate authentication requirement for TLS 1.2 connections
Configure server to not require client certificates for TLS 1.2
Enforce TLS 1.3
allDisable TLS 1.2 and require TLS 1.3 for all connections
Configure server to only accept TLS 1.3 connections
🧯 If You Can't Patch
- Implement network segmentation to prevent man-in-the-middle attacks
- Use additional authentication layers beyond TLS client certificates
🔍 How to Verify
Check if Vulnerable:
Check wolfSSL version and verify if using TLS 1.2 with client certificate authenticationCheck Version:
wolfssl_version --version or check library headersVerify Fix Applied:
Verify wolfSSL version is 5.7.2 or later and test TLS 1.2 client certificate connections📡 Detection & Monitoring
Log Indicators:
- TLS handshake failures with certificate authentication
- Unexpected TLS version downgrades
Network Indicators:
- Man-in-the-middle activity on TLS 1.2 ports
- Unusual certificate negotiation patterns
SIEM Query:
tls.version="1.2" AND certificate.auth AND (digest.weak OR handshake.failure)