A klibc security update has been released for Ubuntu Linux 14.04 ESM, 16.04 ESM, 18.04 LTS, and 20.04 LTS.

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Ubuntu Security Notice USN-5379-1
April 18, 2022

klibc vulnerabilities
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A security issue affects these releases of Ubuntu and its derivatives:

- Ubuntu 20.04 LTS
- Ubuntu 18.04 LTS
- Ubuntu 16.04 ESM
- Ubuntu 14.04 ESM

Summary:

Several security issues were fixed in klibc.

Software Description:
- klibc: small utilities built with klibc for early boot

Details:

It was discovered that klibc did not properly perform
some mathematical operations, leading to an integer overflow.
An attacker could possibly use this issue to cause a crash,
resulting in a denial of service, or possibly execute
arbitrary code. (CVE-2021-31870)

It was discovered that klibc did not properly handled some
memory allocations on 64 bit systems. An attacker could
possibly use this issue to cause a crash, resulting in a
denial of service, or possibly execute arbitrary code.
(CVE-2021-31871)

It was discovered that klibc did not properly handled some file
sizes values on 32 bit systems. An attacker could possibly use
this issue to cause a crash, resulting in a denial of service,
or possibly execute arbitrary code. (CVE-2021-31872)

It was discovered that klibc did not properly handled some
memory allocations. An attacker could possibly use this issue
to cause a crash, resulting in a denial of service, or possibly
execute arbitrary code. (CVE-2021-31873)

Update instructions:

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

Ubuntu 20.04 LTS:
klibc-utils 2.0.7-1ubuntu5.1
libklibc 2.0.7-1ubuntu5.1

Ubuntu 18.04 LTS:
klibc-utils 2.0.4-9ubuntu2.1
libklibc 2.0.4-9ubuntu2.1

Ubuntu 16.04 ESM:
klibc-utils 2.0.4-8ubuntu1.16.04.4+esm1
libklibc 2.0.4-8ubuntu1.16.04.4+esm1

Ubuntu 14.04 ESM:
klibc-utils 2.0.3-0ubuntu1.14.04.3+esm2
libklibc 2.0.3-0ubuntu1.14.04.3+esm2

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

References:
https://ubuntu.com/security/notices/USN-5379-1
CVE-2021-31870, CVE-2021-31871, CVE-2021-31872, CVE-2021-31873

Package Information:
https://launchpad.net/ubuntu/+source/klibc/2.0.7-1ubuntu5.1
https://launchpad.net/ubuntu/+source/klibc/2.0.4-9ubuntu2.1