Directory traversal vulnerability in the -x (extract) command line option in unarj allows remote attackers to overwrite arbitrary files via an arj archive with filenames that contain .. (dot dot) sequences.
https://exchange.xforce.ibmcloud.com/vulnerabilities/17684
http://www.securityfocus.com/bid/11436
http://www.redhat.com/support/errata/RHSA-2005-007.html
http://www.debian.org/security/2005/dsa-652
http://www.debian.org/security/2005/dsa-628
http://security.gentoo.org/glsa/glsa-200411-29.xml
http://lwn.net/Articles/121827/
http://lists.grok.org.uk/pipermail/full-disclosure/2004-October/027348.html