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.

ProFTPD before 1.3.6b and 1.3.7rc before 1.3.7rc2 allows remote unauthenticated denial-of-service due to incorrect handling of overly long commands because main.c in a child process enters an infinite loop.

ProFTPD before 1.3.5e and 1.3.6 before 1.3.6rc5 controls whether the home directory of a user could contain a symbolic link through the AllowChrootSymlinks configuration option, but checks only the last path component when enforcing AllowChrootSymlinks. Attackers with local access could bypass the AllowChrootSymlinks control by replacing a path component (other than the last one) with a symbolic link. The threat model includes an attacker who is not granted full filesystem access by a hosting provider, but can reconfigure the home directory of an FTP user.

The mod_tls module in ProFTPD before 1.3.5b and 1.3.6 before 1.3.6rc2 does not properly handle the TLSDHParamFile directive, which might cause a weaker than intended Diffie-Hellman (DH) key to be used and consequently allow attackers to have unspecified impact via unknown vectors.