USN-197-1: Shorewall vulnerability

10 October 2005

shorewall vulnerability

A security issue affects these releases of Ubuntu and its derivatives:

  • Ubuntu 5.04
  • Ubuntu 4.10

Software Description


A firewall bypass vulnerability has been found in shorewall. If MACLIST_TTL was set to a value greater than 0 or MACLIST_DISPOSITION was set to “ACCEPT” in /etc/shorewall/shorewall.conf, and a client was positively identified through its MAC address, that client bypassed all other policies/rules in place. This could allow external computers to get access to ports that are intended to be restricted by the firewall policy.

Please note that this does not affect the default configuration, which does not enable MAC based client identification.

Update instructions

The problem can be corrected by updating your system to the following package versions:

Ubuntu 5.04
Ubuntu 4.10

To update your system, please follow these instructions: