A NSS security update has been released for Ubuntu Linux 14.04 ESM and 16.04 ESM.

USN-5168-3: NSS vulnerability

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Ubuntu Security Notice USN-5168-3
December 01, 2021

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

- Ubuntu 16.04 ESM
- Ubuntu 14.04 ESM

Summary:

NSS could be made to crash or run programs if it verified a specially
crafted signature.

Software Description:
- nss: Network Security Service library

Details:

USN-5168-1 fixed a vulnerability in NSS. This update provides
the corresponding update for Ubuntu 14.04 ESM and Ubuntu 16.04 ESM.

Original advisory details:

Tavis Ormandy discovered that NSS incorrectly handled verifying DSA/RSA-PSS
signatures. A remote attacker could use this issue to cause NSS to crash,
resulting in a denial of service, or possibly execute arbitrary code.

Update instructions:

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

Ubuntu 16.04 ESM:
libnss3 2:3.28.4-0ubuntu0.16.04.14+esm1

Ubuntu 14.04 ESM:
libnss3 2:3.28.4-0ubuntu0.14.04.5+esm9

After a standard system update you need to restart any applications that
use NSS, such as Evolution, to make all the necessary changes.

References:
  https://ubuntu.com/security/notices/USN-5168-3
  https://ubuntu.com/security/notices/USN-5168-1
CVE-2021-43527