[USN-3999-1] GnuTLS vulnerabilities

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==========================================================================
Ubuntu Security Notice USN-3999-1
May 30, 2019

gnutls28 vulnerabilities
==========================================================================

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

- Ubuntu 19.04
- Ubuntu 18.10
- Ubuntu 18.04 LTS
- Ubuntu 16.04 LTS

Summary:

Several security issues were fixed in GnuTLS.

Software Description:
- gnutls28: GNU TLS library

Details:

Eyal Ronen, Kenneth G. Paterson, and Adi Shamir discovered that GnuTLS was
vulnerable to a timing side-channel attack known as the "Lucky Thirteen"
issue. A remote attacker could possibly use this issue to perform
plaintext-recovery attacks via analysis of timing data. This issue only
affected Ubuntu 16.04 LTS and Ubuntu 18.04 LTS. (CVE-2018-10844,
CVE-2018-10845, CVE-2018-10846)

Tavis Ormandy discovered that GnuTLS incorrectly handled memory when
verifying certain X.509 certificates. A remote attacker could use this
issue to cause GnuTLS to crash, resulting in a denial of service, or
possibly execute arbitrary code. This issue only affected Ubuntu 18.04 LTS,
Ubuntu 18.10, and Ubuntu 19.04. (CVE-2019-3829)

It was discovered that GnuTLS incorrectly handled certain post-handshake
messages. A remote attacker could use this issue to cause GnuTLS to crash,
resulting in a denial of service, or possibly execute arbitrary code. This
issue only affected Ubuntu 18.10 and Ubuntu 19.04. (CVE-2019-3836)

Update instructions:

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

Ubuntu 19.04:
libgnutls30 3.6.5-2ubuntu1.1

Ubuntu 18.10:
libgnutls30 3.6.4-2ubuntu1.2

Ubuntu 18.04 LTS:
libgnutls30 3.5.18-1ubuntu1.1

Ubuntu 16.04 LTS:
libgnutls30 3.4.10-4ubuntu1.5

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

References:
https://usn.ubuntu.com/usn/usn-3999-1
CVE-2018-10844, CVE-2018-10845, CVE-2018-10846, CVE-2019-3829,
CVE-2019-3836

Package Information:
https://launchpad.net/ubuntu/+source/gnutls28/3.6.5-2ubuntu1.1
https://launchpad.net/ubuntu/+source/gnutls28/3.6.4-2ubuntu1.2
https://launchpad.net/ubuntu/+source/gnutls28/3.5.18-1ubuntu1.1
https://launchpad.net/ubuntu/+source/gnutls28/3.4.10-4ubuntu1.5