OpenPrinting reports:
Due to the service binding to *:631 ( INADDR_ANY ), multiple bugs
in cups-browsed can be exploited in sequence to introduce a
malicious printer to the system. This chain of exploits ultimately
enables an attacker to execute arbitrary commands remotely on the
target machine without authentication when a print job is started.
Posing a significant security risk over the network. Notably, this
vulnerability is particularly concerning as it can be exploited
from the public internet, potentially exposing a vast number of
systems to remote attacks if their CUPS services are enabled.
The vulnerability allows an attacker on the internet to create a
new printer device with arbitrary commands in the PPD file of the
printer. Attacks using mDNS on the local network can also replace an
existing printer. The commands are executed when a user attempts to
print on the malicious device. They run with the privileges of the
user "cups".
It is recommended to disable the cups_browsed service until patches
become available. On FreeBSD this is the default. You can check the
status and disable the service with the following commands:
# service cups_browsed status
# service cups_browsed stop
# service cups_browsed disable
If you choose to leave the service enabled, attacks from the
internet can be blocked by removing the "cups" protocol from the
BrowseRemoteProtocols and BrowseProtocols directives in
/usr/local/etc/cups/cups-browsed.conf. Attacks using mDNS can be
blocked by removing the "dnssd" protocol as well. Access can be
limited to specific IP addresses using BrowseAllow, BrowseDeny, and
BrowseOrder directives as documented in cups-browsed.conf(5). Then
restart the service with the following command:
# service cups_browsed restart