A NSS security update has been released for Ubuntu Linux 20.04 LTS, 19.10, 18.04 LTS, and 16.04 LTS.

USN-4397-1: NSS vulnerabilities

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Ubuntu Security Notice USN-4397-1
June 16, 2020

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

- Ubuntu 20.04 LTS
- Ubuntu 19.10
- Ubuntu 18.04 LTS
- Ubuntu 16.04 LTS

Summary:

Several security issues were fixed in NSS.

Software Description:
- nss: Network Security Service library

Details:

It was discovered that NSS incorrectly handled the TLS State Machine. A
remote attacker could possibly use this issue to cause NSS to hang,
resulting in a denial of service. This issue only affected Ubuntu 18.04 LTS
and Ubuntu 19.10. (CVE-2019-17023)

Cesar Pereida Garcia discovered that NSS incorrectly handled DSA key
generation. A local attacker could possibly use this issue to perform a
timing attack and recover DSA keys. (CVE-2020-12399)

Update instructions:

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

Ubuntu 20.04 LTS:
libnss3 2:3.49.1-1ubuntu1.1

Ubuntu 19.10:
libnss3 2:3.45-1ubuntu2.3

Ubuntu 18.04 LTS:
libnss3 2:3.35-2ubuntu2.8

Ubuntu 16.04 LTS:
libnss3 2:3.28.4-0ubuntu0.16.04.11

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

References:
  https://usn.ubuntu.com/4397-1
CVE-2019-17023, CVE-2020-12399

Package Information:
  https://launchpad.net/ubuntu/+source/nss/2:3.49.1-1ubuntu1.1
  https://launchpad.net/ubuntu/+source/nss/2:3.45-1ubuntu2.3
  https://launchpad.net/ubuntu/+source/nss/2:3.35-2ubuntu2.8
  https://launchpad.net/ubuntu/+source/nss/2:3.28.4-0ubuntu0.16.04.11