Debian Security Advisory

DLA-2209-1 tomcat8 -- LTS security update

Date Reported:
28 May 2020
Affected Packages:
Security database references:
In the Debian bugtracking system: Bug 961209, Bug 952436, Bug 952437, Bug 952438.
In Mitre's CVE dictionary: CVE-2019-17563, CVE-2020-1935, CVE-2020-1938, CVE-2020-9484.
More information:

Several security vulnerabilities have been discovered in the Tomcat servlet and JSP engine.

WARNING: The fix for CVE-2020-1938 may disrupt services that rely on a working AJP configuration. The option secretRequired defaults to true now. You should define a secret in your server.xml or you can revert back by setting secretRequired to false.

  • CVE-2019-17563

    When using FORM authentication with Apache Tomcat there was a narrow window where an attacker could perform a session fixation attack. The window was considered too narrow for an exploit to be practical but, erring on the side of caution, this issue has been treated as a security vulnerability.

  • CVE-2020-1935

    In Apache Tomcat the HTTP header parsing code used an approach to end-of-line parsing that allowed some invalid HTTP headers to be parsed as valid. This led to a possibility of HTTP Request Smuggling if Tomcat was located behind a reverse proxy that incorrectly handled the invalid Transfer-Encoding header in a particular manner. Such a reverse proxy is considered unlikely.

  • CVE-2020-1938

    When using the Apache JServ Protocol (AJP), care must be taken when trusting incoming connections to Apache Tomcat. Tomcat treats AJP connections as having higher trust than, for example, a similar HTTP connection. If such connections are available to an attacker, they can be exploited in ways that may be surprising. Previously Tomcat shipped with an AJP Connector enabled by default that listened on all configured IP addresses. It was expected (and recommended in the security guide) that this Connector would be disabled if not required. . Note that Debian already disabled the AJP connector by default. Mitigation is only required if the AJP port was made accessible to untrusted users.

  • CVE-2020-9484

    When using Apache Tomcat and an attacker is able to control the contents and name of a file on the server; and b) the server is configured to use the PersistenceManager with a FileStore; and c) the PersistenceManager is configured with sessionAttributeValueClassNameFilter="null" (the default unless a SecurityManager is used) or a sufficiently lax filter to allow the attacker provided object to be deserialized; and d) the attacker knows the relative file path from the storage location used by FileStore to the file the attacker has control over; then, using a specifically crafted request, the attacker will be able to trigger remote code execution via deserialization of the file under their control. Note that all of conditions a) to d) must be true for the attack to succeed.

    For Debian 8 Jessie, these problems have been fixed in version 8.0.14-1+deb8u17.

    We recommend that you upgrade your tomcat8 packages.

    Further information about Debian LTS security advisories, how to apply these updates to your system and frequently asked questions can be found at: