A c-ares security update has been released for Ubuntu Linux 16.04 LTS and 18.04 LTS.

[USN-6164-2] c-ares vulnerabilities

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Ubuntu Security Notice USN-6164-2
September 11, 2023

c-ares vulnerabilities
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A security issue affects these releases of Ubuntu and its derivatives:

- Ubuntu 18.04 LTS (Available with Ubuntu Pro)
- Ubuntu 16.04 LTS (Available with Ubuntu Pro)

Summary:

Several security issues were fixed in c-ares.

Software Description:
- c-ares: library for asynchronous name resolution

Details:

USN-6164-1 fixed several vulnerabilities in c-ares. This update provides
the corresponding update for Ubuntu 16.04 LTS and Ubuntu 18.04 LTS.

Original advisory details:

Hannes Moesl discovered that c-ares incorrectly handled certain ipv6
addresses. An attacker could use this issue to cause c-ares to crash,
resulting in a denial of service, or possibly execute arbitrary code.
(CVE-2023-31130)

Xiang Li discovered that c-ares incorrectly handled certain UDP packets. A
remote attacker could possibly use this issue to cause c-res to crash,
resulting in a denial of service. (CVE-2023-32067)

Update instructions:

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

Ubuntu 18.04 LTS (Available with Ubuntu Pro):
libc-ares2 1.14.0-1ubuntu0.2+esm1

Ubuntu 16.04 LTS (Available with Ubuntu Pro):
libc-ares2 1.10.0-3ubuntu0.2+esm2

In general, a standard system update will make all the necessary changes.

References:
https://ubuntu.com/security/notices/USN-6164-2
https://ubuntu.com/security/notices/USN-6164-1
CVE-2023-31130, CVE-2023-32067