A Squid security update has been released for Ubuntu Linux 20.04 LTS, 19.10, 18.04 LTS, and 16.04 LTS.

USN-4356-1: Squid vulnerabilities

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Ubuntu Security Notice USN-4356-1
May 13, 2020

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

- Ubuntu 20.04 LTS
- Ubuntu 19.10
- 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:

Jeriko One discovered that Squid incorrectly handled certain Edge Side
Includes (ESI) responses. A malicious remote server could cause Squid to
crash, possibly poison the cache, or possibly execute arbitrary code.
(CVE-2019-12519, CVE-2019-12521)

It was discovered that Squid incorrectly handled the hostname parameter to
cachemgr.cgi when certain browsers are used. A remote attacker could
possibly use this issue to inject HTML or invalid characters in the
hostname parameter. This issue only affected Ubuntu 16.04 LTS, Ubuntu 18.04
LTS, and Ubuntu 19.10. (CVE-2019-18860)

Clément Berthaux and Florian Guilbert discovered that Squid incorrectly
handled Digest Authentication nonce values. A remote attacker could
use this issue to replay nonce values, or possibly execute arbitrary code.
(CVE-2020-11945)

Update instructions:

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

Ubuntu 20.04 LTS:
squid 4.10-1ubuntu1.1

Ubuntu 19.10:
squid 4.8-1ubuntu2.3

Ubuntu 18.04 LTS:
squid 3.5.27-1ubuntu1.6

Ubuntu 16.04 LTS:
squid 3.5.12-1ubuntu7.11

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

References:
  https://usn.ubuntu.com/4356-1
CVE-2019-12519, CVE-2019-12521, CVE-2019-18860, CVE-2020-11945

Package Information:
  https://launchpad.net/ubuntu/+source/squid/4.10-1ubuntu1.1
  https://launchpad.net/ubuntu/+source/squid/4.8-1ubuntu2.3
  https://launchpad.net/ubuntu/+source/squid3/3.5.27-1ubuntu1.6
  https://launchpad.net/ubuntu/+source/squid3/3.5.12-1ubuntu7.11