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

USN-4561-2: Rack vulnerabilities

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Ubuntu Security Notice USN-4561-2
April 06, 2021

ruby-rack vulnerabilities
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A security issue affects these releases of Ubuntu and its derivatives:

- Ubuntu 20.10
- Ubuntu 20.04 LTS
- Ubuntu 16.04 LTS

Summary:

Rack could be made to expose sensitive information over the network.

Software Description:
- ruby-rack: modular Ruby webserver interface

Details:

USN-4561-1 fixed vulnerabilities in Rack. This update provides the
corresponding update for Ubuntu 16.04 LTS, Ubuntu 20.04 LTS and Ubuntu 20.10.

Original advisory details:

It was discovered that Rack incorrectly handled certain paths. An attacker
could possibly use this issue to obtain sensitive information. This issue
only affected Ubuntu 16.04 LTS, Ubuntu 18.04 LTS and Ubuntu 20.04 LTS.
(CVE-2020-8161)

It was discovered that Rack incorrectly validated cookies. An attacker
could possibly use this issue to forge a secure cookie. (CVE-2020-8184)

Update instructions:

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

Ubuntu 20.10:
ruby-rack 2.1.1-5ubuntu0.1

Ubuntu 20.04 LTS:
ruby-rack 2.0.7-2ubuntu0.1

Ubuntu 16.04 LTS:
ruby-rack 1.6.4-3ubuntu0.2

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

References:
  https://ubuntu.com/security/notices/USN-4561-2
  https://ubuntu.com/security/notices/USN-4561-1
CVE-2020-8161, CVE-2020-8184

Package Information:
  https://launchpad.net/ubuntu/+source/ruby-rack/2.1.1-5ubuntu0.1
  https://launchpad.net/ubuntu/+source/ruby-rack/2.0.7-2ubuntu0.1
  https://launchpad.net/ubuntu/+source/ruby-rack/1.6.4-3ubuntu0.2