The Goobi viewer is a web application that allows digitised material to be displayed in a web browser. From version 23.03 to before version 26.05, SolrTools.cleanUpQuery() strips Solr local-parameter syntax ({!...}) from user-supplied query strings before they reach Solr. Its regex can be bypassed by wrapping the local parameter in a second pair of curly braces ({{!...}}): the outer braces are stripped, the inner {!...} survives intact, and a valid Solr local parameter is forwarded. The flaw is in the shared sanitizer, so it affects any endpoint that routes user input through cleanUpQuery. The double-brace bypass applies from v23.10 (the greedy \{(.+)\} regex); a related bare-!join rewrap path is present. This issue has been patched in version 26.05.