Metacat acts as unintended proxy to backend Apache SOLR engine

Metacat is data repository software that helps researchers preserve, share, and discover data. Prior to 3.4.2, MetacatSolrIndex.query forwards the client-controlled qt parameter through Apache SolrJ from search endpoints such as /d1/mn/v2/query/solr/ to its privileged Solr backend. An unauthenticated client can select the /admin/file handler, and SolrJ reformats the parameter into a request accepted even when handleSelect=false is configured on Solr 7.0 or later. When Solr returns the selected core configuration file, Metacat embeds the raw content in an XML processing error response, disclosing internal files such as solrconfig.xml and enabling infrastructure profiling. This issue is fixed in version 3.4.2.