CVE-2021-4118 Deserialization of Untrusted Data in pytorchlightning/pytorch-lightning

What is CVE-2021-4118?

CVE-2021-4118 is a high-severity unsafe deserialization vulnerability in pytorchlightning/pytorch-lightning, published on 23 Dec 2021. 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 is vulnerable to Deserialization of Untrusted Data

Weakness: CWE-502

Which versions are affected by CVE-2021-4118?

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-2021-4118?

Upgrade pytorch-lightning to 1.6.0 or later.

Upgrade, and only deserialise data from trusted sources or with an allow-list of types. More about Unsafe deserialization.

Is CVE-2021-4118 being exploited?

There is no known exploitation of CVE-2021-4118 in the wild and no public exploit code.

Other vulnerabilities in pytorchlightning/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-2vj5-px25-gjrp, PYSEC-2021-874, PYSEC-2026-3968.