USN-4233-2: GnuTLS update

23 January 2020

gnutls28 update

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

  • Ubuntu 18.04 LTS
  • Ubuntu 16.04 LTS

Summary

USN-4233-1 marked SHA1 as untrusted in GnuTLS with no workaround.

Software Description

  • gnutls28 - GNU TLS library

Details

USN-4233-1 disabled SHA1 being used for digital signature operations in GnuTLS. In certain network environments, certificates using SHA1 may still be in use. This update adds the %VERIFY_ALLOW_BROKEN and %VERIFY_ALLOW_SIGN_WITH_SHA1 priority strings that can be used to temporarily re-enable SHA1 until certificates can be replaced with a stronger algorithm.

Original advisory details:

As a security improvement, this update marks SHA1 as being untrusted for digital signature operations.

Update instructions

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

Ubuntu 18.04 LTS
libgnutls30 - 3.5.18-1ubuntu1.3
Ubuntu 16.04 LTS
libgnutls30 - 3.4.10-4ubuntu1.7

To update your system, please follow these instructions: https://wiki.ubuntu.com/Security/Upgrades.

In general, a standard system update will make all the necessary changes.

References