Impact

A SQL injection vulnerability exists in the Query Builder's deleteBatch() method. When deleteBatch() is used together with where() conditions, the bound values from the WHERE clause are substituted directly into the generated SQL with their escape flag ignored, so they are never escaped or quoted. If an application passes user-controlled input to where() before calling deleteBatch(), that input is interpreted as SQL rather than as a value, allowing SQL injection.

This affects only the deleteBatch() code path. Regular delete() operations escape where() binds correctly.

Patches

Upgrade to v4.7.4 or later.

Workarounds

If you cannot upgrade immediately:

• Strictly validate and cast values (e.g. numeric IDs) before using them in conditions - though this does not fully protect string conditions.
• Do not pass user-controlled input to where() when using deleteBatch().
• For user-controlled conditions, use a normal delete() with Query Builder binds instead of deleteBatch().
• Where possible, express required matching values through the batch data and onConstraint() rather than as separate user-controlled where() clauses.

References

• OWASP - SQL Injection (attack reference): https://owasp.org/www-community/attacks/SQL_Injection
• deleteBatch() documentation: https://codeigniter.com/user_guide/database/query_builder.html#builder-deletebatch