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.