A Squid 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-4895-1
March 29, 2021

squid, squid3 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 Squid.

Software Description:
- squid: Web proxy cache server
- squid3: Web proxy cache server

Details:

Alex Rousskov and Amit Klein discovered that Squid incorrectly handled
certain Content-Length headers. A remote attacker could possibly use this
issue to perform an HTTP request smuggling attack, resulting in cache
poisoning. This issue only affected Ubuntu 20.04 LTS. (CVE-2020-15049)

Jianjun Chen discovered that Squid incorrectly validated certain input. A
remote attacker could use this issue to perform HTTP Request Smuggling and
possibly access services forbidden by the security controls.
(CVE-2020-25097)

Update instructions:

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

Ubuntu 20.10:
squid 4.13-1ubuntu2.1

Ubuntu 20.04 LTS:
squid 4.10-1ubuntu1.3

Ubuntu 18.04 LTS:
squid 3.5.27-1ubuntu1.10

Ubuntu 16.04 LTS:
squid 3.5.12-1ubuntu7.16

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

References:
  https://ubuntu.com/security/notices/USN-4895-1
CVE-2020-15049, CVE-2020-25097

Package Information:
  https://launchpad.net/ubuntu/+source/squid/4.13-1ubuntu2.1
  https://launchpad.net/ubuntu/+source/squid/4.10-1ubuntu1.3
  https://launchpad.net/ubuntu/+source/squid3/3.5.27-1ubuntu1.10
  https://launchpad.net/ubuntu/+source/squid3/3.5.12-1ubuntu7.16g