The DEC UDK processing feature in the xterm terminal emulator in XFree86 4.2.99.4 and earlier allows attackers to cause a denial of service via a certain character escape sequence that causes the terminal to enter a tight loop.
http://www.securityfocus.com/bid/6950
http://www.redhat.com/support/errata/RHSA-2003-067.html
http://www.redhat.com/support/errata/RHSA-2003-066.html
http://www.redhat.com/support/errata/RHSA-2003-065.html
http://www.redhat.com/support/errata/RHSA-2003-064.html
http://www.iss.net/security_center/static/11415.php
http://www.debian.org/security/2003/dsa-380
http://marc.info/?l=bugtraq&m=104612710031920&w=2
http://archives.neohapsis.com/archives/vulnwatch/2003-q1/0093.html