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CVE-2020-1938

Publication date 24 February 2020

Last updated 21 August 2024

Ubuntu priority

Low

Why this priority?

Cvss 3 Severity Score

9.8 · Critical

Score breakdown

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. In Apache Tomcat 9.0.0.M1 to 9.0.0.30, 8.5.0 to 8.5.50 and 7.0.0 to 7.0.99, 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. This vulnerability report identified a mechanism that allowed: - returning arbitrary files from anywhere in the web application - processing any file in the web application as a JSP Further, if the web application allowed file upload and stored those files within the web application (or the attacker was able to control the content of the web application by some other means) then this, along with the ability to process a file as a JSP, made remote code execution possible. It is important to note that mitigation is only required if an AJP port is accessible to untrusted users. Users wishing to take a defence-in-depth approach and block the vector that permits returning arbitrary files and execution as JSP may upgrade to Apache Tomcat 9.0.31, 8.5.51 or 7.0.100 or later. A number of changes were made to the default AJP Connector configuration in 9.0.31 to harden the default configuration. It is likely that users upgrading to 9.0.31, 8.5.51 or 7.0.100 or later will need to make small changes to their configurations.

Read the notes from the security team

Mitigation

mdeslaur> In environments where the AJP connector is enabled, care should mdeslaur> be taken to not expose the AJP port to attackers, either by mdeslaur> using a firewall to block the AJP port, or by binding it to mdeslaur> localhost by using address="127.0.0.1" in the AJP configuration.

Status

Package Ubuntu Release Status
tomcat7 24.04 LTS noble Not in release
23.10 mantic Not in release
23.04 lunar Not in release
22.10 kinetic Not in release
22.04 LTS jammy Not in release
21.10 impish Not in release
21.04 hirsute Not in release
20.10 groovy Not in release
20.04 LTS focal Not in release
19.10 eoan Not in release
18.04 LTS bionic Ignored not vulnerable by default
16.04 LTS xenial Ignored not vulnerable by default
14.04 LTS trusty Ignored
tomcat8 24.04 LTS noble Not in release
23.10 mantic Not in release
23.04 lunar Not in release
22.10 kinetic Not in release
22.04 LTS jammy Not in release
21.10 impish Not in release
21.04 hirsute Not in release
20.10 groovy Not in release
20.04 LTS focal Not in release
19.10 eoan Not in release
18.04 LTS bionic Ignored not vulnerable by default
16.04 LTS xenial Ignored not vulnerable by default
14.04 LTS trusty Not in release
tomcat9 24.04 LTS noble
Not affected
23.10 mantic
Not affected
23.04 lunar
Not affected
22.10 kinetic
Not affected
22.04 LTS jammy
Not affected
21.10 impish
Not affected
21.04 hirsute
Not affected
20.10 groovy
Not affected
20.04 LTS focal
Not affected
19.10 eoan Ignored end of life
18.04 LTS bionic Ignored not vulnerable by default
16.04 LTS xenial Not in release
14.04 LTS trusty Not in release

Notes

mdeslaur

In Ubuntu packages, the AJP connector is disabled by default, so unless specifically enabled by an admin, deployments made using the package are not vulnerable to this issue. One of the upstream fixes for this issue renames the requiredSecret parameter to secret and adds a secretRequired parameter that defaults to "true". Adding this change to stable releases will result in servers failing to start until the administrator either changes secretRequired to "false", or configures an adequate secret. Apache starting supporting a secret in mod_proxy_ajp starting with 2.4.42, which means to enable a secret we will have to issue Apache updates with the backported secret support.

Patch details

For informational purposes only. We recommend not to cherry-pick updates. How can I get the fixes?

Package Patch details
tomcat7
tomcat8
tomcat9

Severity score breakdown

Parameter Value
Base score 9.8 · Critical
Attack vector Network
Attack complexity Low
Privileges required None
User interaction None
Scope Unchanged
Confidentiality High
Integrity impact High
Availability impact High
Vector CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H