CVE-2025-7395: wolfSSL Certificate Verification Vulnerability

CVE-2025-7395 Overview

A certificate verification error exists in wolfSSL when building with the WOLFSSL_SYS_CA_CERTS and WOLFSSL_APPLE_NATIVE_CERT_VALIDATION options. This vulnerability causes the wolfSSL client to fail to properly verify the server certificate's domain name, allowing any certificate issued by a trusted Certificate Authority (CA) to be accepted regardless of the hostname. This improper certificate validation flaw (CWE-295) represents a severe security weakness that undermines the fundamental trust model of TLS/SSL communications.

Critical Impact

Attackers with any valid CA-signed certificate can impersonate any server to vulnerable wolfSSL clients, enabling man-in-the-middle attacks and complete interception of encrypted communications.

Affected Products

• wolfSSL library builds with WOLFSSL_SYS_CA_CERTS enabled
• wolfSSL library builds with WOLFSSL_APPLE_NATIVE_CERT_VALIDATION enabled
• Applications using affected wolfSSL configurations on Apple platforms

Discovery Timeline

• 2025-07-18 - CVE CVE-2025-7395 published to NVD
• 2025-07-22 - Last updated in NVD database

Technical Details for CVE-2025-7395

Vulnerability Analysis

This vulnerability represents a critical flaw in the certificate validation logic of wolfSSL's TLS implementation. When wolfSSL is compiled with both WOLFSSL_SYS_CA_CERTS and WOLFSSL_APPLE_NATIVE_CERT_VALIDATION build options, the library fails to perform proper hostname verification against the server certificate's Subject Alternative Name (SAN) or Common Name (CN) fields.

Under normal TLS operation, clients must verify not only that a server's certificate is signed by a trusted CA, but also that the certificate's domain name matches the hostname being connected to. This vulnerability bypasses the hostname check entirely, meaning a certificate issued for attacker.com could be used to impersonate legitimate-bank.com without triggering any validation errors.

The network-accessible nature of this vulnerability allows remote exploitation without any user interaction or authentication requirements. Since the vulnerability affects the fundamental certificate validation mechanism, any application using the vulnerable wolfSSL configuration is susceptible to man-in-the-middle attacks.

Root Cause

The root cause is an improper certificate validation error (CWE-295) in wolfSSL's integration with Apple's native certificate validation APIs. When both WOLFSSL_SYS_CA_CERTS and WOLFSSL_APPLE_NATIVE_CERT_VALIDATION are enabled, the code path that should perform hostname verification is bypassed or returns success without actually checking the hostname against the certificate's domain fields. This creates a dangerous condition where certificate chain validation succeeds, but the critical hostname binding check is missing.

Attack Vector

The attack vector is network-based and requires no user interaction or special privileges. An attacker positioned to intercept network traffic (e.g., on the same network, through DNS poisoning, or via BGP hijacking) can present any valid CA-signed certificate to a vulnerable wolfSSL client. The client will accept the certificate as valid for any hostname, allowing the attacker to:

1. Intercept and decrypt all TLS-protected communications
2. Inject malicious content into responses
3. Capture sensitive credentials and session tokens
4. Perform complete impersonation of any HTTPS server

The vulnerability is particularly dangerous because the attacker only needs a single legitimate certificate from any trusted CA—they do not need to compromise the CA or obtain a certificate for the specific target domain.

Detection Methods for CVE-2025-7395

Indicators of Compromise

• Unexpected TLS certificate mismatches in application logs where connections succeed despite hostname differences
• Network traffic analysis showing certificate Subject Alternative Names that don't match the connection hostname
• Audit logs indicating successful TLS handshakes with certificates issued for unexpected domains
• Anomalous behavior from applications that should be communicating with specific trusted endpoints

Detection Strategies

• Review build configurations for wolfSSL deployments to identify instances using both WOLFSSL_SYS_CA_CERTS and WOLFSSL_APPLE_NATIVE_CERT_VALIDATION flags
• Implement certificate pinning or certificate transparency monitoring to detect unexpected certificates
• Deploy network monitoring to detect TLS connections where presented certificates don't match expected hostnames
• Conduct code audits of applications using wolfSSL on Apple platforms to verify certificate validation logic

Monitoring Recommendations

• Monitor wolfSSL-based applications for TLS connection anomalies and certificate validation events
• Enable verbose TLS logging during security audits to capture certificate details for manual review
• Implement security information and event management (SIEM) rules to alert on certificate validation discrepancies
• Consider deploying network intrusion detection systems (NIDS) with rules for detecting hostname/certificate mismatches

How to Mitigate CVE-2025-7395

Immediate Actions Required

• Audit all wolfSSL deployments to identify builds using both WOLFSSL_SYS_CA_CERTS and WOLFSSL_APPLE_NATIVE_CERT_VALIDATION options
• Disable WOLFSSL_APPLE_NATIVE_CERT_VALIDATION temporarily if possible while awaiting a patch
• Implement application-level certificate pinning as a defense-in-depth measure
• Review the wolfSSL GitHub repository for security updates and patches

Patch Information

Organizations should monitor the wolfSSL GitHub repository for official security patches addressing this vulnerability. Update to a patched version of wolfSSL as soon as one becomes available. Rebuild all affected applications with the patched wolfSSL library and redeploy to production environments. Verify the fix by testing that certificate hostname validation is enforced properly after the update.

Workarounds

• Disable WOLFSSL_APPLE_NATIVE_CERT_VALIDATION in build configurations and use alternative certificate validation methods
• Implement certificate pinning at the application level to restrict accepted certificates to known-good values
• Add manual hostname verification in application code to supplement wolfSSL's validation
• Consider using alternative TLS libraries temporarily for critical applications until a patch is available
• Restrict network exposure of affected applications to trusted network segments

# Configuration example
# Rebuild wolfSSL without the vulnerable configuration options
./configure --disable-sys-ca-certs
make clean && make
make install

# Verify build configuration excludes vulnerable options
grep -E "WOLFSSL_SYS_CA_CERTS|WOLFSSL_APPLE_NATIVE_CERT_VALIDATION" config.log