The FreeRADIUS server relies on OpenSSL to perform certificate
validation, including Certificate Revocation List (CRL) checks. The
FreeRADIUS usage of OpenSSL, in CRL application, limits the checks
to leaf certificates, therefore not detecting revocation of
intermediate CA certificates.
An unexpired client certificate, issued by an intermediate CA with
a revoked certificate, is therefore accepted by FreeRADIUS.
Specifically sets the X509_V_FLAG_CRL_CHECK flag for leaf
certificate CRL checks, but does not use X509_V_FLAG_CRL_CHECK_ALL
for CRL checks on the complete trust chain.
The FreeRADIUS project advises that the recommended configuration
is to use self-signed CAs for all EAP-TLS methods.