Affected Users:
Anyone using wolfSSL on Apple platforms with versions after 5.6.4 and before 5.8.0, specifically when built with WOLFSSL_SYS_CA_CERTS and WOLFSSL_APPLE_NATIVE_CERT_VALIDATION enabled (default for non-macOS Apple targets when using autotools or CMake).
Summary:
When using system CA certificates and Apple native certificate validation on Apple platforms, the native trust store verification routine incorrectly overrides errors produced elsewhere in the wolfSSL certificate verification process. This includes critical failures such as hostname matching/SNI verification, OCSP validation, CRL checks, and other certificate chain verification errors.
This vulnerability allows any trusted certificate chain to override security errors that should have resulted in termination of the TLS connection. An attacker with a valid certificate for one domain could potentially intercept connections meant for other domains, despite hostname verification failures. Similarly, revoked certificates could continue to be accepted if the certificate chain remains in the trust store.
The issue exists because the native validation result takes precedence over wolfSSL’s internal security checks. When the native validation succeeds, it returns success regardless of previous errors detected by wolfSSL’s verification process.
Recommendation:
If building for an Apple platform with native certificate validation enabled and performing TLS connections expecting certificate verification, then it is recommended to update the version of wolfSSL used (v5.8.2 or later).
Additional Details:
The patch fixing this issue can be viewed at:
Special thanks to Thomas Leong from ExpressVPN for responsibly disclosing this vulnerability.
If you have questions about any of the above, please contact us at facts@wolfSSL.com or call us at +1 425 245 8247.
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