With the default settings, the Flash Player does not seek the user's permission to store local shared objects on the hard disk.
By default, an SWF application running in Flash Player from version 9 to 11 (as of Sept 1, 2011) may store up to 100 kB of data to the user's hard drive.
[7] On 10 August 2009, Wired magazine reported that more than half of the top websites used local shared objects to track users and store information about them, but only four of them mentioned it in their privacy policy.
[8] According to the New York Times, by July 2010 there had been at least five class-action lawsuits in the United States against media companies for using local shared objects.
For instance, CCleaner, a standalone computer program for Microsoft Windows and Mac OS X, allows users to delete local shared objects on demand.
Since at least April 2012 (v 11.2.202.233), updating by downloading a new Flash version resets the security and privacy settings to the defaults of allowing local storage and asking for media access again, which may be against users' wishes.
[19] However, two years passed since its introduction until Adobe, on March 7, 2011, announced that Flash Player v10.3, which was still in development at the time, supports co-operating with Internet Explorer 8 or later to delete local shared objects.
[21] Four months later, Adobe announced that Flash Player 10.3 enables Mozilla Firefox 4 and "future releases of Apple Safari and Google Chrome" to delete local shared objects,[20] so since version 4, Firefox treats LSOs the same way as HTTP cookies - deletion rules that previously applied only to HTTP cookies now also apply to LSOs.
[25][26] The resulting support requests cannot be solved favorably for Mozilla Firefox users without changes to the browser, because of the introduced equivalence between HTTP and flash cookies.
[22][23] Currently, the workaround in use is to either configure the browser to never clear history data and cookies or to revert the part of the changes affecting this use case, using third-party patches.