Cisco IOS using Cisco Express Forwarding could allow an attacker to obtain sensitive information

ios-cef-information-leak (8296) The risk level is classified as MediumMedium Risk


Cisco devices running some could allow a remote attacker to obtain sensitive information dropped from previous packets. If a remote attacker sends a malformed packet to the affected device with an IP level packet length that is greater than the MAC level packet length, the router would increase the packet size to the length indicated by the IP level by inserting arbitrary data that had been dropped by previous packets. This could allow an attacker to obtain sensitive information.


Obtain Information


Upgrade to the latest version of Cisco IOS appropriate for your system, as listed in Cisco Systems Inc. Security Advisory, February 27, 2002. See References.

As a workaround, disable CEF.


Platforms Affected:

  • Cisco IOS 11.1CC
  • Cisco IOS 12.0
  • Cisco IOS 12.0S
  • Cisco IOS 12.0ST
  • Cisco IOS 12.0T
  • Cisco IOS 12.1
  • Cisco IOS 12.1E
  • Cisco IOS 12.1T
  • Cisco IOS 12.2
  • Cisco IOS 12.2T


Feb 27, 2002

The information within this database may change without notice. Use of this information constitutes acceptance for use in an AS IS condition. There are NO warranties, implied or otherwise, with regard to this information or its use. Any use of this information is at the user's risk. In no event shall the author/distributor (IBM Internet Security Systems X-Force) be held liable for any damages whatsoever arising out of or in connection with the use or spread of this information.

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