RHSA-2009:1238 - Security Advisory

Topic

An updated dnsmasq package that fixes two security issues is now available
for Red Hat Enterprise Linux 5.

This update has been rated as having important security impact by the Red
Hat Security Response Team.

Description

Dnsmasq is a lightweight and easy to configure DNS forwarder and DHCP
server.

Core Security Technologies discovered a heap overflow flaw in dnsmasq when
the TFTP service is enabled (the "--enable-tftp" command line option, or by
enabling "enable-tftp" in "/etc/dnsmasq.conf"). If the configured tftp-root
is sufficiently long, and a remote user sends a request that sends a long
file name, dnsmasq could crash or, possibly, execute arbitrary code with
the privileges of the dnsmasq service (usually the unprivileged "nobody"
user). (CVE-2009-2957)

A NULL pointer dereference flaw was discovered in dnsmasq when the TFTP
service is enabled. This flaw could allow a malicious TFTP client to crash
the dnsmasq service. (CVE-2009-2958)

Note: The default tftp-root is "/var/ftpd", which is short enough to make
it difficult to exploit the CVE-2009-2957 issue; if a longer directory name
is used, arbitrary code execution may be possible. As well, the dnsmasq
package distributed by Red Hat does not have TFTP support enabled by
default.

All users of dnsmasq should upgrade to this updated package, which contains
a backported patch to correct these issues. After installing the updated
package, the dnsmasq service must be restarted for the update to take
effect.

Solution

Before applying this update, make sure that all previously-released
errata relevant to your system have been applied.

This update is available via Red Hat Network. Details on how to use
the Red Hat Network to apply this update are available at
http://kbase.redhat.com/faq/docs/DOC-11259

Affected Products

• Red Hat Enterprise Linux Server 5 x86_64
• Red Hat Enterprise Linux Server 5 ia64
• Red Hat Enterprise Linux Server 5 i386
• Red Hat Enterprise Linux for x86_64 - Extended Update Support 5.3 x86_64
• Red Hat Enterprise Linux for x86_64 - Extended Update Support 5.3 ia64
• Red Hat Enterprise Linux for x86_64 - Extended Update Support 5.3 i386
• Red Hat Enterprise Linux Server - AUS 5.3 x86_64
• Red Hat Enterprise Linux Server - AUS 5.3 ia64
• Red Hat Enterprise Linux Server - AUS 5.3 i386
• Red Hat Enterprise Linux Workstation 5 x86_64
• Red Hat Enterprise Linux Workstation 5 i386
• Red Hat Enterprise Linux Desktop 5 x86_64
• Red Hat Enterprise Linux Desktop 5 i386
• Red Hat Enterprise Linux for IBM z Systems 5 s390x
• Red Hat Enterprise Linux for IBM z Systems - Extended Update Support 5.3 s390x
• Red Hat Enterprise Linux for Power, big endian 5 ppc
• Red Hat Enterprise Linux for Power, big endian - Extended Update Support 5.3 ppc
• Red Hat Enterprise Linux Server from RHUI 5 x86_64
• Red Hat Enterprise Linux Server from RHUI 5 i386

Fixes

• BZ - 519020 - CVE-2009-2957, CVE-2009-2958 dnsmasq: multiple vulnerabilities in TFTP server

CVEs

• CVE-2009-2957
• CVE-2009-2958

References

• http://www.redhat.com/security/updates/classification/#important