Dnsmasq: Multiple vulnerabilities

Background

Dnsmasq is a lightweight, easy to configure DNS forwarder and DHCP server. It includes support for Trivial FTP (TFTP).

Description

Multiple vulnerabilities have been reported in the TFTP functionality included in Dnsmasq:

• Pablo Jorge and Alberto Solino discovered a heap-based buffer overflow (CVE-2009-2957).
• An anonymous researcher reported a NULL pointer reference (CVE-2009-2958).

Impact

A remote attacker in the local network could exploit these vulnerabilities by sending specially crafted TFTP requests to a machine running Dnsmasq, possibly resulting in the remote execution of arbitrary code with the privileges of the user running the daemon, or a Denial of Service. NOTE: The TFTP server is not enabled by default.

Workaround

You can disable the TFTP server either at buildtime by not enabling the “tftp” USE flag, or at runtime. Make sure “–enable-tftp” is not set in the DNSMASQ_OPTS variable in the /etc/conf.d/dnsmasq file and “enable-tftp” is not set in /etc/dnsmasq.conf, either of which would enable TFTP support if it is compiled in.

Resolution

All Dnsmasq users should upgrade to the latest version:

 # emerge --sync
 # emerge --ask --oneshot --verbose ">=net-dns/dnsmasq-2.5.0"