One way to defeat a multi-level security solution is to leak data via

A 'bypass regulator' is not a recognized security or networking term relevant to defeating multi-level security solutions.

Steganography hides data within another medium (e.g., images), but it does not inherently exploit the shared resource mechanisms that MLS systems control, making it a different class of technique.

A covert channel communicates information by manipulating shared system resources (such as timing, storage, or CPU usage) in ways that violate the MLS security policy, bypassing the formal access control model. Because MLS systems enforce mandatory access controls between classification levels, covert channels are specifically designed to circumvent those controls without triggering them. They are a fundamental threat recognized in the Bell-LaPadula model and the Trusted Computer System Evaluation Criteria.

Asymmetric routing is a network forwarding concept where traffic takes different paths in each direction, and it does not relate to leaking data across MLS classification boundaries.