Vulnerability Note VU#656315

Cisco IOS vulnerable to DoS via crafted PPTP packet sent to port 1723/tcp

Original Release date: 29 Jul 2001 | Last revised: 23 Feb 2004


Cisco IOS contains a vulnerability that allows an intruder to crash the router.


By sending a specially crafted PPTP packet to port 1723, an intruder can crash a device running a vulnerable version of IOS. Quoting from the Cisco Advisory:

    By sending a crafted PPTP packet to a port 1723, a control PPTP port, it is possible to crash the router. This vulnerability does not require special router configuration. Enabling PPTP is sufficient to expose the vulnerability. The router will crash after it receives a single packet.

For more information, see the Cisco Advisory.


An intruder can cause a vulnerable router to crash.


Upgrade to a later version of IOS as documented in the Cisco Advisory.

Systems Affected (Learn More)

VendorStatusDate NotifiedDate Updated
Cisco Systems Inc.Affected-29 Jul 2001
If you are a vendor and your product is affected, let us know.

CVSS Metrics (Learn More)

Group Score Vector
Base N/A N/A
Temporal N/A N/A
Environmental N/A N/A



Thanks to Cisco for the information contained in their advisory, upon which this document is based.

This document was written by Shawn V. Hernan.

Other Information

  • CVE IDs: CVE-2001-1183
  • Date Public: 12 Jul 2001
  • Date First Published: 29 Jul 2001
  • Date Last Updated: 23 Feb 2004
  • Severity Metric: 20.79
  • Document Revision: 5


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