Certain BSD-based Telnet clients, including those used on Solaris and SuSE Linux, allow remote malicious Telnet servers to read sensitive environment variables via the NEW-ENVIRON option with a SEND ENV_USERVAR command.
https://oval.cisecurity.org/repository/search/definition/oval%3Aorg.mitre.oval%3Adef%3A1139
https://oval.cisecurity.org/repository/search/definition/oval%3Aorg.mitre.oval%3Adef%3A11373
http://www.vupen.com/english/advisories/2006/3101
http://www.us-cert.gov/cas/techalerts/TA06-214A.html
http://www.securityfocus.com/bid/19289
http://www.securityfocus.com/bid/13940
http://www.redhat.com/support/errata/RHSA-2005-562.html
http://www.redhat.com/support/errata/RHSA-2005-504.html
http://www.novell.com/linux/security/advisories/2005_16_sr.html
http://www.kb.cert.org/vuls/id/800829
http://sunsolve.sun.com/search/document.do?assetkey=1-26-57761-1
http://sunsolve.sun.com/search/document.do?assetkey=1-26-57755-1
http://sunsolve.sun.com/search/document.do?assetkey=1-26-101671-1
http://sunsolve.sun.com/search/document.do?assetkey=1-26-101665-1
http://securitytracker.com/id?1014203
http://secunia.com/advisories/21253
http://secunia.com/advisories/17135
http://lists.apple.com/archives/security-announce/2006//Aug/msg00000.html
http://idefense.com/application/poi/display?id=260&type=vulnerabilities