Hydra: hydra.utils.instantiate with untrusted config can lead to code execution

Summary

hydra.utils.instantiate() resolves and calls Python objects from config. If an

application passes untrusted config to instantiate(), an attacker who controls

_target_ and its arguments can cause arbitrary code execution in the consuming

process.

Hydra is not a network service. Exploitation requires a consuming application,

library, or user workflow to load attacker-controlled config, CLI overrides, or

model metadata and pass it to hydra.utils.instantiate().

Details

Hydra's instantiate API is designed to construct objects and call functions from

configuration. For example:

component:
  _target_: package.module.Class
  arg: value