Vulnerability Note VU#446689

Check Point FireWall-1 allows fragmented packets through firewall if Fast Mode is enabled

Original Release date: 05 Jan 2001 | Last revised: 30 Aug 2001


If any rules include the "Fast Mode" option, Check Point Firewall-1 and VPN-1 will incorrectly allow unauthorized connection attempts to hosts that should be restricted.


A feature called "Fast Mode" (or "FASTPATH"), included in Check Point FireWall-1 and VPN-1 is designed to improve performance in older versions of these products. Unfortunately, a system with this feature enabled in any rules may not adequately protect systems from specially malformed TCP fragment packets. The Fast Mode feature is disabled by default. Specifically, an intruder can make unauthorized connection attempts to hosts they know the IP address for.

More information about this vulnerability is available from Check Point's web site:

The "Fast Mode" feature is scheduled to be discontinued in the next release of the Check Point FireWall-1 and VPN-1 products.


An intruder who knows the IP address of a protected host can make unauthorized connection attempts to the host.


Upgrade your product to version 4.1-SP3 or 4.0-SP8.

Turn off "Fast Mode" in all rule sets. This change is not needed if you upgrade to 4.1-SP3 or 4.0-SP8.

Systems Affected (Learn More)

VendorStatusDate NotifiedDate Updated
Check PointAffected05 Jan 200106 Feb 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



The information contained in this vulnerability note was obtained from the Check Point security advisory on this topic.

This document was written by Cory F Cohen.

Other Information

  • CVE IDs: Unknown
  • Date Public: 19 Dec 2000
  • Date First Published: 05 Jan 2001
  • Date Last Updated: 30 Aug 2001
  • Severity Metric: 26.04
  • Document Revision: 8


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