The Tor Project has fixed a flaw in its anonymization and privacy software that leaked information from memory on some machines running Tor that could give an attacker access to sensitive information stored in the cache. The issue was caused by the way that some compilers handle a specific function in the Tor client. Tor software is designed to protect users privacy and anonymity through the use of a large network of nodes that encrypt traffic and bring it out the other side in a way that makes it difficult for eavesdroppers to see where the traffic originated.
Source: https://threatpost.com/memory-bug-fixed-tor-client-110912/77203/