Apparently, Firefox24 uses its own umask (0077) setting for downloaded files (in libxul.so ?) , whereas Firexfox23 seems to use the inherited umask from the calling process (0022 in my case). Securitywise this is change fine, but in my case I need to use my own umask setting. Anyway to specifies this ? (had checked about:config) thanks ! Note:question https://support.mozilla.org/en-US/questions/971876?esab=a&as=aaq seems related, but IMHO an existing directory hasn't a umask setting.