A Ruby security update has been released for Ubuntu 20.04 LTS.

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Ubuntu Security Notice USN-4922-2
April 26, 2021

ruby2.7 vulnerability
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A security issue affects these releases of Ubuntu and its derivatives:

- Ubuntu 20.04

Summary:

Ruby incorrectly handled XML documents.

Software Description:
- ruby2.7: Object-oriented scripting language

Details:

USN-4922-1 fixed a vulnerability in Ruby. This update provides the
corresponding update for Ubuntu 21.04.

Original advisory details:

Juho Nurminen discovered that the REXML gem bundled with Ruby incorrectly
parsed and serialized XML documents. A remote attacker could possibly use
this issue to perform an XML round-trip attack.

Update instructions:

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

Ubuntu 20.04:
libruby2.7 2.7.2-4ubuntu1.1
ruby2.7 2.7.2-4ubuntu1.1

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

References:
  https://ubuntu.com/security/notices/USN-4922-2
  https://ubuntu.com/security/notices/USN-4922-1
CVE-2021-28965

Package Information:
  https://launchpad.net/ubuntu/+source/ruby2.7/2.7.2-4ubuntu1.1