Security vulnerabilities in JavaScript have been used to [deanonymize Tor Browser in the past](https://arstechnica.com/information-technology/2013/08/attackers-wield-firefox-exploit-to-uncloak-anonymous-tor-users/).
This is because, in Tails, *Tor Browser* is confined using *[[!debwiki AppArmor]]* to protect your files from some types of attacks against *Tor Browser*.
For example, thanks to this confinement, even if an attacker manages to exploit a security vulnerability in *Tor Browser*, they wouldn't be able to access all the content of your Persistent Storage.
<p>To prevent Tails from running out of memory and crashing, download very big files to the <em>Persistent/Tor Browser</em> folder. All the files that you download outside of the Persistent Storage are stored in memory (RAM), which is more limited.</p>