USN-4922-2: Ruby vulnerability

USN-4922-2: Ruby vulnerability

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.
Source: USN-4922-2: Ruby vulnerability