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Ubuntu Security Notice USN-4596-1
October 21, 2020

tomcat9 vulnerabilities
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A security issue affects these releases of Ubuntu and its derivatives:

- Ubuntu 20.04 LTS

Summary:

Several security issues were fixed in Tomcat.

Software Description:
- tomcat9: Apache Tomcat 9 - Servlet and JSP engine

Details:

It was discovered that Tomcat did not properly manage HTTP/2 streams. An
attacker could possibly use this to cause Tomcat to consume resources,
resulting in a denial of service. (CVE-2020-11996)

It was discovered that Tomcat did not properly release the HTTP/1.1
processor after the upgrade to HTTP/2. An attacker could possibly use
this to generate an OutOfMemoryException, resulting in a denial of
service. (CVE-2020-13934)

It was discovered that Tomcat did not properly validate the payload
length in a WebSocket frame. An attacker could possibly use this to
trigger an infinite loop, resulting in a denial of service. (CVE-2020-13935)

It was discovered that Tomcat did not properly deserialize untrusted
data. An attacker could possibly use this issue to execute arbitrary
code. (CVE-2020-9484)

Update instructions:

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

Ubuntu 20.04 LTS:
  libtomcat9-embed-java           9.0.31-1ubuntu0.1
  libtomcat9-java                 9.0.31-1ubuntu0.1
  tomcat9                         9.0.31-1ubuntu0.1
  tomcat9-common                  9.0.31-1ubuntu0.1

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

References:
  https://usn.ubuntu.com/4596-1
  CVE-2020-11996, CVE-2020-13934, CVE-2020-13935, CVE-2020-9484

Package Information:
  https://launchpad.net/ubuntu/+source/tomcat9/9.0.31-1ubuntu0.1