deserialization flaw in session persistence storage leading to RCE
CVE: CVE-2020-9484
Component: tomcat
CWE: CWE-502
Severity: Important
CVSS v3: 7.0/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H
Release date: 2020-05-20T00:00:00+00:00

A deserialization flaw was discovered in Apache Tomcat's use of a FileStore. Under specific circumstances, an attacker can use a specially crafted request to trigger Remote Code Execution through deserialization of the file under their control. The highest threat from the vulnerability is to data confidentiality and integrity as well as system availability.

Statement: In Red Hat Enterprise Linux 8, Red Hat Certificate System 10 and Identity Management are using the pki-servlet-engine component, which embeds a vulnerable version of Tomcat. However, in these specific contexts, the prerequisites to the vulnerability are not met. The PersistentManager is not set, and a SecurityManager is used. The use of pki-servlet-engine outside of these contexts is not supported. As a result, the vulnerability can not be triggered in supported configurations of these products. A future update may update Tomcat in pki-servlet-engine.

Red Hat Satellite do not ship Tomcat and rather use its configuration. The product is not affected because configuration does not make use of PersistanceManager or FileStore. Tomcat updates can be obtain from Red Hat Enterprise Linux (RHEL) RHSA.

Remediation:
Before applying this update, make sure all previously released errata
relevant to your system have been applied.

For details on how to apply this update, refer to:

https://access.redhat.com/articles/11258
Before applying this update, make sure all previously released errata
relevant to your system have been applied.

For details on how to apply this update, refer to:

https://access.redhat.com/articles/11258
Before applying the update, back up your existing installation, including all applications, configuration files, databases and database settings, and so on.

Installation instructions are available from the Fuse 7.11.0 product documentation page:
https://access.redhat.com/documentation/en-us/red_hat_fuse/7.11/
Before applying the update, back up your existing installation, including all applications, configuration files, databases and database settings, and so on.

Installation instructions are available from the Fuse 7.9.0 product
documentation page:
https://access.redhat.com/documentation/en-us/red_hat_fuse/7.9/
Before applying the update, back up your existing installation, including all applications, configuration files, databases and database settings, and so on.

The References section of this erratum contains a download link for the update. You must be logged in to download the update.
Before applying the update, back up your existing installation, including all applications, configuration files, databases and database settings, and so on.

The References section of this erratum contains a download link for the update. You must be logged in to download the update.
Before applying the update, back up your existing installation, including all applications, configuration files, databases and database settings, and so on.

The References section of this erratum contains a download link (you must log in to download the update).
Users may configure the PersistenceManager with an appropriate value for sessionAttributeValueClassNameFilter to ensure that only application provided attributes are serialized and deserialized.  For more details about the configuration, refer to the Apache Tomcat 9 Configuration Reference https://tomcat.apache.org/tomcat-9.0-doc/config/manager.html.