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Ubuntu Security Notice USN-5168-4
December 07, 2021

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

- Ubuntu 16.04 ESM
- Ubuntu 14.04 ESM

Summary:

USN-5168-3 introduced a regression in NSS.

Software Description:
- nss: Network Security Service library

Details:

USN-5168-3 fixed a vulnerability in NSS. Unfortunately that update introduced
a regression that could break SSL connections. This update fixes the problem.

We apologize for the inconvenience.

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+esm2

Ubuntu 14.04 ESM:
  libnss3                         2:3.28.4-0ubuntu0.14.04.5+esm10

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-5168-4
  https://ubuntu.com/security/notices/USN-5168-1
  CVE-2021-43527