SearchStax Cloud – Recommended Mitigation for Solr Vulnerability from CVE-2022-39135

Recommended Mitigation for Solr Vulnerability

The NIST National Vulnerability Database has published a new vulnerability – CVE-2022-39135, which affects Apache Solr versions 6.5 to 8.11.2. This vulnerability is classified as Critical with a CVSS score of 9.8.

Description of Solr Vulnerability – CVE-2022-39135

Apache Calcite has a vulnerability, CVE-2022-39135, that is exploitable in Apache Solr in SolrCloud mode. If an untrusted user can supply SQL queries to Solr’s “/sql” handler (even indirectly via proxies / other apps), then the user could perform an XML External Entity (XXE) attack.

An XXE attack may lead to the disclosure of confidential data, denial of service, server-side request forgery (SSRF), port scanning from the Solr node, and other system impacts.

Apache Solr versions 6.5 to 8.11.2 are affected by this vulnerability.

Recommended Mitigation for CVE-2022-39135

As recommended by the Apache Solr website, any of the following steps should help prevent this vulnerability from being exploited in your Solr deployment:

  1. Protect your Solr instance against unauthorized access 
  2. If you do not use JDBC/the “/sql” handler, it it recommended to disable it by adding the following to your solrconfig.xml:
<requestHandler name="/sql" class="solr.NotFoundRequestHandler"/>

We recommend adding this configuration just before the SearchHandler section around line 697. (Your line numbers may differ.)

What Do I Need to Do to Prevent Vulnerability to CVE-2022-39135?

SearchStax Cloud provides Cloud Private environments, IP Filtering, and Basic Authentication to secure your deployments and recommends using these Security settings whenever possible.

  • Review all your Solr deployments – SearchStax customers should review all deployments (production and non-production) and ensure they are protected by IP Filtering and/or Basic Authentication. You can access these settings from SearchStax Dashboard. For more information, refer to SearchStax Cloud documentation for Securing Solr Deployments with SearchStax Cloud.
  • Disable /sql Handler – If you do not use the /sql handler, then you should disable it in your solrconfig.xml file. Note that the “/sql” handler is a Solr implicit handler. So, even if you do not have “/sql” handler defined in your configs, it is present and you would need to disable it. Please see the How can I update my Solr Configuration page for instructions on how to update your config files.
  • Sitecore Plugin has already disabled “/sql” handler – SearchStax has updated the default configs used by the Sitecore Plugin to disable the “/sql” handler.  

If you have any other questions about the Solr Vulnerability, please contact SearchStax Support or submit a support ticket.