Functions that create temporary file names (such as tempfile.mktemp and os.tempnam) are fundamentally insecure, as they do not ensure exclusive access to a file with the temporary name they return. The file name returned by these functions is guaranteed to be unique on creation but the file must be opened in a separate operation. There is no guarantee that the creation and open operations will happen atomically. This provides an opportunity for an attacker to interfere with the file before it is opened.

Note that mktemp has been deprecated since Python 2.3.

Replace the use of mktemp with some of the more secure functions in the tempfile module, such as TemporaryFile. If the file is intended to be accessed from other processes, consider using the NamedTemporaryFile function.

The following piece of code opens a temporary file and writes a set of results to it. Because the file name is created using mktemp, another process may access this file before it is opened using open.

By changing the code to use NamedTemporaryFile instead, the file is opened immediately.

Python Standard Library: tempfile.mktemp.