Kysely is a type-safe TypeScript SQL query builder. Versions up to and including 0.28.11 has a SQL injection vulnerability in JSON path compilation for MySQL and SQLite dialects. The `visitJSONPathLeg()` function appends user-controlled values from `.key()` and `.at()` directly into single-quoted JSON path string literals (`'$.key'`) without escaping single quotes. An attacker can break out of the JSON path string context and inject arbitrary SQL. This is inconsistent with `sanitizeIdentifier()`, which properly doubles delimiter characters for identifiers — both are non-parameterizable SQL constructs requiring manual escaping, but only identifiers are protected. Version 0.28.12 fixes the issue.