A Tomcat security update has been released for Ubuntu Linux 16.04 LTS.

USN-4557-1: Tomcat vulnerabilities

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Ubuntu Security Notice USN-4557-1
September 30, 2020

tomcat6 vulnerabilities
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A security issue affects these releases of Ubuntu and its derivatives:

- Ubuntu 16.04 LTS

Summary:

Several security issues were fixed in Tomcat.

Software Description:
- tomcat6: Servlet and JSP engine

Details:

It was discovered that the Tomcat realm implementations incorrectly handled
passwords when a username didn't exist. A remote attacker could possibly
use this issue to enumerate usernames. (CVE-2016-0762)

Alvaro Munoz and Alexander Mirosh discovered that Tomcat incorrectly
limited use of a certain utility method. A malicious application could
possibly use this to bypass Security Manager restrictions. (CVE-2016-5018)

It was discovered that Tomcat incorrectly controlled reading system
properties. A malicious application could possibly use this to bypass
Security Manager restrictions. (CVE-2016-6794)

It was discovered that Tomcat incorrectly controlled certain configuration
parameters. A malicious application could possibly use this to bypass
Security Manager restrictions. (CVE-2016-6796)

It was discovered that Tomcat incorrectly limited access to global JNDI
resources. A malicious application could use this to access any global JNDI
resource without an explicit ResourceLink. (CVE-2016-6797)

Regis Leroy discovered that Tomcat incorrectly filtered certain invalid
characters from the HTTP request line. A remote attacker could possibly
use this issue to inject data into HTTP responses. (CVE-2016-6816)

Pierre Ernst discovered that the Tomcat JmxRemoteLifecycleListener did not
implement a recommended fix. A remote attacker could possibly use this
issue to execute arbitrary code. (CVE-2016-8735)

Update instructions:

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

Ubuntu 16.04 LTS:
libservlet2.5-java 6.0.45+dfsg-1ubuntu0.1

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

References:
  https://usn.ubuntu.com/4557-1
CVE-2016-0762, CVE-2016-5018, CVE-2016-6794, CVE-2016-6796,
CVE-2016-6797, CVE-2016-6816, CVE-2016-8735

Package Information:
  https://launchpad.net/ubuntu/+source/tomcat6/6.0.45+dfsg-1ubuntu0.1