CVE-2026-50636: LimeSurvey RemoteControl invite_participants/remind_participants SQL Injection

The RemoteControl API methods invite_participants and remind_participants pass a caller-supplied token-ID array into TokenDynamic::findUninvited(), which concatenates the values directly into a tid IN ('...') SQL clause without parameterization or input validation. A remote, authenticated attacker holding the tokens/update permission on a survey can inject a crafted array element to perform SQL injection. Because LimeSurvey configures its PDO connection with emulated prepared statements (emulatePrepare = true) and does not disable MySQL multi-statements, the injection supports stacked queries: the attacker can append arbitrary additional statements (INSERT/UPDATE/DELETE/DROP/CREATE) after the original SELECT. This permits both arbitrary read of any data in the database, such as administrator bcrypt password hashes (lime_users), survey response PII, session records, and global settings, all recoverable via a SLEEP() time-based blind oracle, and arbitrary write/destruction of that data, including directly overwriting the administrator password hash for immediate account takeover or dropping/truncating tables. Reads and writes extend to any schema the application's database user can access. The RemoteControl interface (RPCInterface = json/xml) must be enabled, which is not the default.