USN-4698-2: Dnsmasq regression

Releases

• Ubuntu 20.10
• Ubuntu 20.04 LTS
• Ubuntu 18.04 ESM
• Ubuntu 16.04 ESM

Packages

• dnsmasq - Small caching DNS proxy and DHCP/TFTP server

Details

USN-4698-1 fixed vulnerabilities in Dnsmasq. The updates introduced
regressions in certain environments related to issues with multiple
queries, and issues with retries. This update fixes the problem.

Original advisory details:

Moshe Kol and Shlomi Oberman discovered that Dnsmasq incorrectly handled
memory when sorting RRsets. A remote attacker could use this issue to cause
Dnsmasq to hang, resulting in a denial of service, or possibly execute
arbitrary code. (CVE-2020-25681, CVE-2020-25687)

Moshe Kol and Shlomi Oberman discovered that Dnsmasq incorrectly handled
extracting certain names. A remote attacker could use this issue to cause
Dnsmasq to hang, resulting in a denial of service, or possibly execute
arbitrary code. (CVE-2020-25682, CVE-2020-25683)

Moshe Kol and Shlomi Oberman discovered that Dnsmasq incorrectly
implemented address/port checks. A remote attacker could use this issue to
perform a cache poisoning attack. (CVE-2020-25684)

Moshe Kol and Shlomi Oberman discovered that Dnsmasq incorrectly
implemented query resource name checks. A remote attacker could use this
issue to perform a cache poisoning attack. (CVE-2020-25685)

Moshe Kol and Shlomi Oberman discovered that Dnsmasq incorrectly handled
multiple query requests for the same resource name. A remote attacker could
use this issue to perform a cache poisoning attack. (CVE-2020-25686)

It was discovered that Dnsmasq incorrectly handled memory during DHCP
response creation. A remote attacker could possibly use this issue to
cause Dnsmasq to consume resources, leading to a denial of service. This
issue only affected Ubuntu 16.04 LTS, Ubuntu 18.04 LTS, and Ubuntu 20.04
LTS. (CVE-2019-14834)

Update instructions

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

Ubuntu 20.10

• dnsmasq - 2.82-1ubuntu1.2
• dnsmasq-base - 2.82-1ubuntu1.2
• dnsmasq-utils - 2.82-1ubuntu1.2

Ubuntu 20.04

• dnsmasq - 2.80-1.1ubuntu1.3
• dnsmasq-base - 2.80-1.1ubuntu1.3
• dnsmasq-utils - 2.80-1.1ubuntu1.3

Ubuntu 18.04

• dnsmasq - 2.79-1ubuntu0.3
• dnsmasq-base - 2.79-1ubuntu0.3
• dnsmasq-utils - 2.79-1ubuntu0.3

Ubuntu 16.04

• dnsmasq - 2.75-1ubuntu0.16.04.8
• dnsmasq-base - 2.75-1ubuntu0.16.04.8
• dnsmasq-utils - 2.75-1ubuntu0.16.04.8

After a standard system update you need to reboot your computer to make
all the necessary changes.

References

• https://launchpad.net/bugs/1916462