Live › vulnerability › GHSA-wf6j-7hvr-gr93
Go to dashboardHydra's legacy instantiate() blacklist omits PyYAML's unsafe loading functions, so a config-controlled target such as yaml.unsafe_load can run Python code when an application passes untrusted targets and arguments into it. The configured callable runs with the application's process privileges, and the same pattern can arise from a third-party model whose bundled configuration is loaded by the app.
Summary written from the sources below. Check the originals before acting.
First seen by InfraStack 2026-10-27 17:11 UTC. All times on this page are UTC.
Applications that pass attacker-controlled targets or arguments into Hydra's legacy instantiate() or call(), including loaders that read configuration bundled with a third-party model. Projects that only use Hydra with their own trusted configuration files, or that already use Hydra 1.4's execution whitelist, are less exposed; the sources do not say how common the model-loading pattern is in real loaders.
| Product | Ecosystem | Affected | Fixed in |
|---|---|---|---|
| hydra-core | pypi | >= 1.3.6, < 1.3.8 | 1.3.8 |
| hydra-core | pypi | >= 1.4.0.dev9, < 1.4.0rc3 | 1.4.0rc3 |
pip show hydra-core and check whether the version is 1.3.6 or 1.3.7, or a 1.4 prerelease 1.4.0.dev9, 1.4.0.dev10, 1.4.0rc1 or 1.4.0rc2.instantiate( or call( from hydra and check whether any config passed to them comes from users, uploads or downloaded model metadata.1.3.8 on the 1.3 line.1.4.0rc3 on the 1.4 line.instantiate() or call(); for Hydra 1.4, supply a narrow execution whitelist from trusted Python code.Each row is the first time that source carried this signal. The analyst’s rows are its own findings.
Hydra's legacy target blacklist omits PyYAML's unsafe loading surfaces. If an application passes attacker-controlled targets and arguments to instantiate(), a target such as yaml.unsafe_load can execute Python code through a config-controlled YAML stream containing Python object-construction tags.
The attacker must control the relevant target and arguments that the application instantiates. The configured callable executes with the application's process privileges. This is a gap in the best-effort legacy blacklist. It is not a bypass of Hydra 1.4's execution whitelist supplied by trusted Python code.
One realistic exposure is a model downloaded from a third-party repository, such as Hugging Face, that bundles attacker-controlled configuration. When a victim loads the model using application code that passes this configuration to legacy Hydra instantiation without effective target restrictions, the model's metadata can execute code in the victim process. This model-loading attack pattern is documented in the original Hydra advisory GHSA-2cp2-2r3c-7p7r and the associated Unit 42 research. It does not imply that all Hugging Face models or currently patched downstream loaders are affected.
Hydra 1.3's blacklist is defense in depth, not a complete security boundary. Hydra 1.4 is affected on its deprecated no-whitelist legacy path. Installed application wrappers can perform indirect operations beyond a name-based blacklist's coverage; this fix does not make arbitrary configuration safe.
The unsafe_load finding is directly reproduced. PyYAML 6.0.3 full_load rejects the demonstrated python/object/apply payload, so the finding does not claim that all PyYAML loading APIs execute that payload.
The fix blocks the yaml. target namespace except for the exact yaml.safe_load, yaml.safe_load_all, yaml.safe_dump, and yaml.safe_dump_all functions. Loader classes, constructor registration, general dump/load APIs, and other targets in the namespace remain blocked. Existing canonical-identity checks also cover aliases. The fix preserves Hydra 1.4's explicit unsafe opt-out for trusted use.
Do not pass untrusted configuration to instantiate() or call(). For Hydra 1.4, supply a narrow execution whitelist from trusted Python code. Do not let untrusted configuration select its own execution policy or opt out of checks.
The reported incomplete-remediation stable range is hydra-core 1.3.6 through 1.3.7. The 1.4 prerelease legacy path is also affected, including 1.4.0.dev9, 1.4.0.dev10, 1.4.0rc1, and 1.4.0rc2. The related blacklist advisory GHSA-rqx7-p7vv-w7hr was first patched in 1.3.6 and 1.4.0.dev9; these ranges describe the remaining omission after that remediation.
Reported by zx (@manus-pi).
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