.. Licensed under the Apache License, Version 2.0 (the "License"); you may not
.. use this file except in compliance with the License. You may obtain a copy of
.. the License at
..
..   http://www.apache.org/licenses/LICENSE-2.0
..
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.. WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
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.. the License.

.. _cve/2018-11769:

====================================================
CVE-2018-11769: Apache CouchDB Remote Code Execution
====================================================

:Date: 08.08.2018

:Affected: Apache CouchDB 1.x and ≤2.1.2

:Severity: Low

:Vendor: The Apache Software Foundation

Description
===========

CouchDB administrative users can configure the database server via HTTP(S). Due
to insufficient validation of administrator-supplied configuration settings via
the HTTP API, it is possible for a CouchDB administrator user to escalate their
privileges to that of the operating system’s user under which CouchDB runs, by
bypassing the blacklist of configuration settings that are not allowed to be
modified via the HTTP API.

This privilege escalation effectively allows a CouchDB admin user to gain
arbitrary remote code execution, bypassing mitigations for
:ref:`CVE-2017-12636 <cve/2017-12636>` and :ref:`CVE-2018-8007 <cve/2018-8007>`.

Mitigation
==========

All users should upgrade to CouchDB :ref:`2.2.0 <release/2.2.0>`.

Upgrades from previous 2.x versions in the same series should be seamless.

Users still on CouchDB 1.x should be advised that the Apache CouchDB team no
longer support 1.x.

In-place mitigation (on any 1.x release, or 2.x prior to 2.2.0) is possible by
removing the ``_config`` route from the ``default.ini`` file, as follows:

   .. code-block:: text

    [httpd_global_handlers]
    ;_config = {couch_httpd_misc_handlers, handle_config_req}

or by blocking access to the `/_config` (1.x) or `/_node/*/_config` routes at a reverse
proxy in front of the service.