Tor before 0.2.0.32 does not properly process the (1) User and (2) Group configuration options, which might allow local users to gain privileges by leveraging unintended supplementary group memberships of the Tor process.
https://exchange.xforce.ibmcloud.com/vulnerabilities/47101
http://www.vupen.com/english/advisories/2008/3366
http://www.securityfocus.com/bid/32648
http://security.gentoo.org/glsa/glsa-200904-11.xml
http://secunia.com/advisories/34583