CVE-2026-58659 PyTorch Lightning Arbitrary Code Execution via _instantiator Hyperparameter

What is CVE-2026-58659?

CVE-2026-58659 is a high-severity code injection vulnerability in Lightning-AI pytorch-lightning, published on 15 Jul 2026. It can only be exploited from the same machine or local network, and only if a user opens a file or follows a link.

Official description

PyTorch Lightning through 2.6.5, fixed in commit d710d68, contains a remote code execution vulnerability in the _load_state function that imports and executes attacker-controlled module names from checkpoint _instantiator hyperparameters. Attackers can craft malicious checkpoint files that bypass weights_only=True protections to execute arbitrary code when LightningModule.load_from_checkpoint is called.

Weakness: CWE-470

Which versions are affected by CVE-2026-58659?

4 open source packages ship an affected version, including pytorch-lightning and lightning. It affects 1 product.

Products include Lightningai Pytorch Lightning.

How do I fix CVE-2026-58659?

Upgrade pytorch-lightning to 2.6.6 or later.

Upgrade, and never evaluate templates, expressions or code built from user input. More about Code injection.

Is CVE-2026-58659 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-58659 exists.

Other vulnerabilities in Lightning-AI pytorch-lightning

• CVE-2024-5452 RCE via Property/Class Pollution in lightning-ai/pytorch-lightning Critical 9.8
• CVE-2026-44484 Compromise of PyTorch Lightning PyPi Package Versions Critical 9.3
• CVE-2024-8019 Arbitrary File Write/Overwrite in lightning-ai/pytorch-lightning Critical 9.1
• CVE-2024-5980 Arbitrary File Write via /v1/runs API endpoint in lightning-ai/pytorch-lightning Critical 9.1
• CVE-2026-31221 PyTorch Lightning load_from_checkpoint has an insecure checkpoint deserialization High 8.8

Sources

• CVE record
• NVD
• OSV
• GitHub advisory
• How this page is made

Also known as GHSA-qqmf-gpg7-g8gw, PYSEC-2026-3624, PYSEC-2026-3967.