=========================================================================Ubuntu Security Notice USN-5235-1
January 18, 2022

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

- Ubuntu 21.10
- Ubuntu 21.04
- Ubuntu 20.04 LTS
- Ubuntu 18.04 LTS
- Ubuntu 16.04 ESM

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 Ruby incorrectly handled certain HTML files.
An attacker could possibly use this issue to cause a crash. This
issue only affected Ubuntu 20.04 LTS, Ubuntu 21.04, and Ubuntu 21.10.
(CVE-2021-41816)

It was discovered that Ruby incorrectly handled certain regular expressions.
An attacker could possibly use this issue to cause a regular expression
denial of service. (CVE-2021-41817)

It was discovered that Ruby incorrectly handled certain cookie names.
An attacker could possibly use this issue to access or expose
sensitive information. (CVE-2021-41819)

Update instructions:

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

Ubuntu 21.10:
  ruby2.7                         2.7.4-1ubuntu3.1

Ubuntu 21.04:
  ruby2.7                         2.7.2-4ubuntu1.3

Ubuntu 20.04 LTS:
  ruby2.7                         2.7.0-5ubuntu1.6

Ubuntu 18.04 LTS:
  ruby2.5                         2.5.1-1ubuntu1.11

Ubuntu 16.04 ESM:
  ruby2.3                         2.3.1-2~ubuntu16.04.16+esm2

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

References:
  https://ubuntu.com/security/notices/USN-5235-1
  CVE-2021-41816, CVE-2021-41817, CVE-2021-41819

Package Information:
  https://launchpad.net/ubuntu/+source/ruby2.7/2.7.4-1ubuntu3.1
  https://launchpad.net/ubuntu/+source/ruby2.7/2.7.2-4ubuntu1.3
  https://launchpad.net/ubuntu/+source/ruby2.7/2.7.0-5ubuntu1.6
  https://launchpad.net/ubuntu/+source/ruby2.5/2.5.1-1ubuntu1.11