A Ruby security update has been released for Ubuntu Linux 16.04 LTS, 18.04 LTS, 20.04 LTS, and 20.10.

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Ubuntu Security Notice USN-4882-1
March 18, 2021

ruby2.3, ruby2.5, ruby2.7 vulnerabilities
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A security issue affects these releases of Ubuntu and its derivatives:

- Ubuntu 20.10
- Ubuntu 20.04 LTS
- Ubuntu 18.04 LTS
- Ubuntu 16.04 LTS

Summary:

Several security issues were fixed in Ruby.

Software Description:
- ruby2.7: Object-oriented scripting language
- ruby2.5: Object-oriented scripting language
- ruby2.3: Object-oriented scripting language

Details:

It was discovered that the Ruby JSON gem incorrectly handled certain JSON
files. If a user or automated system were tricked into parsing a specially
crafted JSON file, a remote attacker could use this issue to execute
arbitrary code. This issue only affected Ubuntu 16.04 LTS and Ubuntu 18.04
LTS. (CVE-2020-10663)

It was discovered that Ruby incorrectly handled certain socket memory
operations. A remote attacker could possibly use this issue to obtain
sensitive information. This issue only affected Ubuntu 18.04 LTS and
Ubuntu 20.04 LTS. (CVE-2020-10933)

It was discovered that Ruby incorrectly handled certain transfer-encoding
headers when using Webrick. A remote attacker could possibly use this issue
to bypass a reverse proxy. (CVE-2020-25613)

Update instructions:

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

Ubuntu 20.10:
libruby2.7 2.7.1-3ubuntu1.2
ruby2.7 2.7.1-3ubuntu1.2

Ubuntu 20.04 LTS:
libruby2.7 2.7.0-5ubuntu1.3
ruby2.7 2.7.0-5ubuntu1.3

Ubuntu 18.04 LTS:
libruby2.5 2.5.1-1ubuntu1.8
ruby2.5 2.5.1-1ubuntu1.8

Ubuntu 16.04 LTS:
libruby2.3 2.3.1-2~ubuntu16.04.15
ruby2.3 2.3.1-2~ubuntu16.04.15

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

References:
  https://ubuntu.com/security/notices/USN-4882-1
CVE-2020-10663, CVE-2020-10933, CVE-2020-25613

Package Information:
  https://launchpad.net/ubuntu/+source/ruby2.7/2.7.1-3ubuntu1.2
  https://launchpad.net/ubuntu/+source/ruby2.7/2.7.0-5ubuntu1.3
  https://launchpad.net/ubuntu/+source/ruby2.5/2.5.1-1ubuntu1.8
  https://launchpad.net/ubuntu/+source/ruby2.3/2.3.1-2~ubuntu16.04.15