rad_decode in FreeRADIUS 0.9.2 and earlier allows remote attackers to cause a denial of service (crash) via a short RADIUS string attribute with a tag, which causes memcpy to be called with a -1 length argument, as demonstrated using the Tunnel-Password attribute.
https://oval.cisecurity.org/repository/search/definition/oval%3Aorg.mitre.oval%3Adef%3A10917
http://www.redhat.com/support/errata/RHSA-2003-386.html
http://marc.info/?l=freeradius-users&m=106947389449613&w=2