hydra-optuna-sweeper accepted a configuration-controlled dotted path in
hydra.sweeper.custom_search_space, resolved it with the lower-level
hydra.utils.get_method() API, and later invoked the returned callable.
Hydra's object-lookup helpers intentionally trust their input and do not apply
the execution policy used by instantiate() and logging configuration. As a
result, untrusted Optuna multirun configuration could select installed Python
code for execution in the Hydra controller process.
Exploitation requires control of an application's Optuna sweep configuration or command-line overrides and an importable callable in the application's environment. Selected code runs with the privileges of the application.
On affected Hydra 1.4 development releases, this path bypasses an execution whitelist provided by trusted application code. Hydra 1.3 has no execution-whitelist security boundary; there, the same change restores the legacy blocklist as defense in depth.
The Optuna sweeper now resolves the configured callback through
hydra.utils.instantiate() as a partial callable. On Hydra 1.4, the active
execution whitelist therefore authorizes the callback before use. On Hydra
1.3, the legacy blocklist is applied as defense in depth.
The public get_object(), get_method(), get_static_method(), and
get_class() helpers remain lower-level trusted-input APIs. Their documentation
now warns against passing values derived from untrusted configuration and
directs config-driven construction to instantiate().
hydra-optuna-sweeper>= 1.2.0, < 1.3.01.3.0>= 1.4.0.dev4, < 1.4.0.dev101.4.0.dev10The feature was introduced in 1.2.0 and is absent from the 1.1 release line.
The 1.4 development line was affected from 1.4.0.dev4 through 1.4.0.dev9.
Treat Optuna sweep configuration and command-line overrides as trusted. Do not
set custom_search_space from externally controlled input or allow untrusted
users to place modules on the application import path.
Reported by zx (GitHub: @manus-pi).
{
"cwe_ids": [
"CWE-470"
],
"github_reviewed": true,
"github_reviewed_at": "2026-10-07T20:24:02Z",
"nvd_published_at": "2026-10-06T19:18:12Z",
"severity": "HIGH"
}