GNU Emacs version 25.3.1 (and other versions most likely) ignores umask when creating a backup save file ("[ORIGINAL_FILENAME]~") resulting in files that may be world readable or otherwise accessible in ways not intended by the user running the emacs binary.
Stack-based buffer overflow in emacs allows user-assisted attackers to cause a denial of service (application crash) and possibly have unspecified other impact via a large precision value in an integer format string specifier to the format function, as demonstrated via a certain "emacs -batch -eval" command line.