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Ubuntu Security Notice USN-4168-1
October 29, 2019

libidn2 vulnerabilities
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A security issue affects these releases of Ubuntu and its derivatives:

- Ubuntu 19.04
- Ubuntu 18.04 LTS

Summary:

Several security issues were fixed in Libidn2.

Software Description:
- libidn2: Internationalized domain names (IDNA2008/TR46) command line tool

Details:

It was discovered that Libidn2 incorrectly handled certain inputs.
A attacker could possibly use this issue to impersonate domains.
(CVE-2019-12290)

It was discovered that Libidn2 incorrectly handled certain inputs.
An attacker could possibly use this issue to execute arbitrary code.
(CVE-2019-18224)

Update instructions:

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

Ubuntu 19.04:
  idn2                            2.0.5-1ubuntu0.3
  libidn2-0                       2.0.5-1ubuntu0.3

Ubuntu 18.04 LTS:
  idn2                            2.0.4-1.1ubuntu0.2
  libidn2-0                       2.0.4-1.1ubuntu0.2

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

References:
  https://usn.ubuntu.com/4168-1
  CVE-2019-12290, CVE-2019-18224

Package Information:
  https://launchpad.net/ubuntu/+source/libidn2/2.0.5-1ubuntu0.3
  https://launchpad.net/ubuntu/+source/libidn2/2.0.4-1.1ubuntu0.2