A GNU C Library security update has been released for Ubuntu Linux 16.04 LTS.

USN-4954-1: GNU C Library vulnerabilities

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Ubuntu Security Notice USN-4954-1
May 14, 2021

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

- Ubuntu 16.04 LTS

Summary:

Several security issues were fixed in GNU C Library.

Software Description:
- glibc: GNU C Library

Details:

Jason Royes and Samuel Dytrych discovered that the memcpy()
implementation for 32 bit ARM processors in the GNU C Library contained
an integer underflow vulnerability. An attacker could possibly use
this to cause a denial of service (application crash) or execute
arbitrary code. (CVE-2020-6096)

It was discovered that the POSIX regex implementation in the GNU C
Library did not properly parse alternatives. An attacker could use this
to cause a denial of service. (CVE-2009-5155)

Update instructions:

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

Ubuntu 16.04 LTS:
libc6 2.23-0ubuntu11.3

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

References:
  https://ubuntu.com/security/notices/USN-4954-1
CVE-2009-5155, CVE-2020-6096