CVE-2019-19269

An issue was discovered in tls_verify_crl in ProFTPD through 1.3.6b. A dereference of a NULL pointer may occur. This pointer is returned by the OpenSSL sk_X509_REVOKED_value() function when encountering an empty CRL installed by a system administrator. The dereference occurs when validating the certificate of a client connecting to the server in a TLS client/server mutual-authentication setup.