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CVE-2000-0268
https://notcve.org/view.php?id=CVE-2000-0268
20 Apr 2000 — Cisco IOS 11.x and 12.x allows remote attackers to cause a denial of service by sending the ENVIRON option to the Telnet daemon before it is ready to accept it, which causes the system to reboot. • http://www.cisco.com/warp/public/707/iostelnetopt-pub.shtml •
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CVE-1999-0445
https://notcve.org/view.php?id=CVE-1999-0445
01 Apr 1999 — In Cisco routers under some versions of IOS 12.0 running NAT, some packets may not be filtered by input access list filters. • http://www.osvdb.org/1104 •
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CVE-1999-0063 – Cisco IOS 12.0.2 - Syslog Crash
https://notcve.org/view.php?id=CVE-1999-0063
11 Jan 1999 — Cisco IOS 12.0 and other versions can be crashed by malicious UDP packets to the syslog port. • https://www.exploit-db.com/exploits/19531 •
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CVE-1999-0157
https://notcve.org/view.php?id=CVE-1999-0157
18 Aug 1998 — Cisco PIX firewall and CBAC IP fragmentation attack results in a denial of service. • http://www.osvdb.org/1097 •