Open Policy Agent (OPA) is an open source, general-purpose policy engine. The Rego compiler provides a (deprecated)
WithUnsafeBuiltins function, which allows users to provide a set of built-in functions that should be deemed unsafe by the compiler if encountered in the policy compilation stage. A bypass of this protection has been found, where the use of the
with keyword to mock such a built-in function (a feature introduced in OPA v0.40.0), is not taken into account by
WithUnsafeBuiltins. Multiple conditions need to be met in order to create an adverse effect. Version 0.43.1 contains a patch for this issue. As a workaround, avoid using the
WithUnsafeBuiltins function and use the
capabilities feature instead.