SEPPmail Secure Email Gateway versions before 15.1.1 contain a critical vulnerability where the software trusts file paths supplied in externally provided Large File Transfer (LFT) attachment metadata. This flaw allows an unauthenticated remote sender to cause the mail-processing worker, which runs as root, to disclose, move, or delete accessible regular files when LFT is enabled and the message is processed through the affected secure-mail path.