[security] directory traversal in tempfile prefix

GitHub fields:

assignee = None
closed_at = None
created_at = <Date 2018-11-19.12:46:03.177>
labels = ['type-security', '3.8', '3.9', '3.10', '3.7', 'library']
title = '[security] directory traversal in tempfile prefix'
updated_at = <Date 2021-03-14.02:25:00.048>
user = 'https://bugs.python.org/YusukeEndoh'

bugs.python.org fields:

activity = <Date 2021-03-14.02:25:00.048>
actor = 'gregory.p.smith'
assignee = 'none'
closed = False
closed_date = None
closer = None
components = ['Library (Lib)']
creation = <Date 2018-11-19.12:46:03.177>
creator = 'Yusuke Endoh'
dependencies = []
files = ['47939']
hgrepos = []
issue_num = 35278
keywords = ['patch']
message_count = 6.0
messages = ['330097', '330100', '330169', '335174', '340205', '356299']
nosy_count = 7.0
nosy_names = ['mjpieters', 'vstinner', 'lukasz.langa', 'cheryl.sabella', 'Yusuke Endoh', 'thorleon', 'obestwalter']
pr_nums = ['10627']
priority = 'normal'
resolution = None
stage = 'patch review'
status = 'open'
superseder = None
type = 'security'
url = 'https://bugs.python.org/issue35278'
versions = ['Python 3.6', 'Python 3.7', 'Python 3.8', 'Python 3.9', 'Python 3.10']