CVE-2018-12713: gimp: predictable temporary file name in test-xcf.c unit test

Severity: Critical

CVSS Score: 9.1

GIMP through 2.10.2 makes g_get_tmp_dir calls to establish temporary filenames, which may result in a filename that already exists, as demonstrated by the gimp_write_and_read_file function in app/tests/test-xcf.c. This might be leveraged by attackers to overwrite files or read file content that was intended to be private.