=========================================================================Ubuntu Security Notice USN-5104-1
October 05, 2021

squid, squid3 vulnerability
=========================================================================
A security issue affects these releases of Ubuntu and its derivatives:

- Ubuntu 21.04
- Ubuntu 20.04 LTS
- Ubuntu 18.04 LTS

Summary:

Squid could be made to crash or expose sensitive information over the
network.

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

Details:

Lyu discovered that Squid incorrectly handled WCCP protocol data. A remote
attacker could use this issue to cause Squid to crash, resulting in a
denial of service, or possibly obtain sensitive information.

Update instructions:

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

Ubuntu 21.04:
  squid                           4.13-1ubuntu4.2

Ubuntu 20.04 LTS:
  squid                           4.10-1ubuntu1.5

Ubuntu 18.04 LTS:
  squid                           3.5.27-1ubuntu1.12

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

References:
  https://ubuntu.com/security/notices/USN-5104-1
  CVE-2021-28116

Package Information:
  https://launchpad.net/ubuntu/+source/squid/4.13-1ubuntu4.2
  https://launchpad.net/ubuntu/+source/squid/4.10-1ubuntu1.5
  https://launchpad.net/ubuntu/+source/squid3/3.5.27-1ubuntu1.12