CVE-2026-106440: CWE-470: Use of Externally-Controlled Input to Select Classes or Code ('Unsafe Reflection') in hydra-ecosystem hydra

Hydra versions >=1.2.0 <1.3.0 and >=1.4.0.dev4 <1.4.0.dev10 contain a vulnerability in the hydra-optuna-sweeper package where the configuration-controlled dotted path in hydra.sweeper.custom_search_space is resolved using hydra.utils.get_method() without applying the usual execution policy. This allows an attacker who can control Optuna sweep configuration or command-line overrides to select importable Python code for execution with the application's privileges, effectively bypassing trusted execution whitelists. The vulnerability is categorized as CWE-470 (Use of Externally-Controlled Input to Select Classes or Code, 'Unsafe Reflection'). It is fixed in versions 1.3.0 and 1.4.0.dev10.

An attacker with the ability to control Optuna sweep configuration or command-line overrides can execute arbitrary Python code within the context of the hydra application process. This can lead to full compromise of the application, including confidentiality, integrity, and availability impacts as indicated by the CVSS vector (C:H/I:H/A:H). The vulnerability bypasses trusted execution whitelists, increasing the risk of unauthorized code execution.

This vulnerability is fixed in hydra versions 1.3.0 and 1.4.0.dev10. Users should upgrade to these versions or later to remediate the issue. No other mitigation or temporary workaround is indicated in the available data.