Core Security Technologies discovered a heap overflow vulnerability in dnsmasq when the TFTP service is enabled ('--enable-tftp'). If the configured tftp-prefix is sufficiently long, and a remote user sent a request which sends a long file name, dnsmasq could crash or, possibly, execute arbitrary code with root privileges.
The default tftp-prefix is /var/tftpd, which is short enough to make this difficult to exploit; if a longer prefix is used then arbitrary code execution may be possible. As well, Red Hat does not have TFTP support enabled by default.
CORE has provided two CVE names:
CVE-2009-2957 for the heap overflow issue they found (possibly arbitrary code execution).
CVE-2009-2958 for the NULL-pointer dereference Steve found (remote DoS).
The disclosure date is August 31st.
This is not a critical issue. dnsmasq starts up as root but by default drops privileges to run as user nobody. Because it runs non-privileged, and because of the non-default configuration requirements (i.e. enabling TFTP requires running dnsmasq without the initscript or modifying the initscript to enable it), as well as the fact that dnsmasq should realistically only ever be available to the local area network and not the internet-at-large, makes this an important impact issue.
Embargo is lifted; 2.50 is available:
This issue has been addressed in following products:
Red Hat Enterprise Linux 5
Via RHSA-2009:1238 https://rhn.redhat.com/errata/RHSA-2009-1238.html
Core Security advisory:
dnsmasq-2.46-3.fc11 has been pushed to the Fedora 11 stable repository. If problems still persist, please make note of it in this bug report.
dnsmasq-2.46-2.fc10 has been pushed to the Fedora 10 stable repository. If problems still persist, please make note of it in this bug report.