CVE-2018-11769: Apache CouchDB Remote Code Execution (affects versions 1.x and ≤2.1.2)

[Joan Touzet <wohali () apache org>]

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 CVE-2017-12636 and CVE-2018-8007.


Mitigation
==========

All users should upgrade to CouchDB 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:

    [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.