A Squid security update has been released for Ubuntu Linux 19.10, 19.04, 18.04 LTS, and 16.04 LTS

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Ubuntu Security Notice USN-4213-1
December 04, 2019

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

- Ubuntu 19.10
- Ubuntu 19.04
- 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 and Kristoffer Danielsson discovered that Squid incorrectly
handled certain URN requests. A remote attacker could possibly use this
issue to bypass access checks and access restricted servers. This issue was
only addressed in Ubuntu 19.04 and Ubuntu 19.10. (CVE-2019-12523)

Jeriko One discovered that Squid incorrectly handed URN responses. A remote
attacker could use this issue to cause Squid to crash, resulting in a
denial of service, or possibly execute arbitrary code. (CVE-2019-12526)

Alex Rousskov discovered that Squid incorrectly handled certain strings. A
remote attacker could possibly use this issue to cause Squid to crash,
resulting in a denial of service. This issue only affected Ubuntu 19.04.
(CVE-2019-12854)

Jeriko One and Kristoffer Danielsson discovered that Squid incorrectly
handled certain input. A remote attacker could use this issue to cause
Squid to crash, resulting in a denial of service, or possibly execute
arbitrary code. This issue was only addressed in Ubuntu 19.04 and Ubuntu
19.10. (CVE-2019-18676)

Kristoffer Danielsson discovered that Squid incorrectly handled certain
messages. This issue could result in traffic being redirected to origins
it should not be delivered to. (CVE-2019-18677)

Régis Leroy discovered that Squid incorrectly handled certain HTTP
request headers. A remote attacker could use this to smuggle HTTP requests
and corrupt caches with arbitrary content. (CVE-2019-18678)

David Fifield discovered that Squid incorrectly handled HTTP Digest
Authentication. A remote attacker could possibly use this issue to obtain
pointer contents and bypass ASLR protections. (CVE-2019-18679)

Update instructions:

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

Ubuntu 19.10:
squid 4.8-1ubuntu2.1

Ubuntu 19.04:
squid 4.4-1ubuntu2.3

Ubuntu 18.04 LTS:
squid3 3.5.27-1ubuntu1.4

Ubuntu 16.04 LTS:
squid3 3.5.12-1ubuntu7.9

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

References:
https://usn.ubuntu.com/4213-1
CVE-2019-12523, CVE-2019-12526, CVE-2019-12854, CVE-2019-18676,
CVE-2019-18677, CVE-2019-18678, CVE-2019-18679

Package Information:
https://launchpad.net/ubuntu/+source/squid/4.8-1ubuntu2.1
https://launchpad.net/ubuntu/+source/squid/4.4-1ubuntu2.3
https://launchpad.net/ubuntu/+source/squid3/3.5.27-1ubuntu1.4
https://launchpad.net/ubuntu/+source/squid3/3.5.12-1ubuntu7.9