What’s Vulnerable › Vulnerabilities

CVE-2026-31221

• Severity: high (CVSS 7.8 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.4% probability of exploitation in the next 30 days
• Public exploit or detection template: yes
• Published: 2026-05-12 · updated 2026-06-17
• Weakness: CWE-502

Description

PyTorch-Lightning versions 2.6.0 and earlier contain an insecure deserialization vulnerability (CWE-502) in the checkpoint loading mechanism. The LightningModule.load_from_checkpoint() method, which is commonly used to load saved model states, internally calls torch.load() without setting the security-restrictive weights_only=True parameter. This default behavior allows the deserialization of arbitrary Python objects via the Pickle module. A remote attacker can exploit this by providing a maliciously crafted checkpoint file, leading to arbitrary code execution on the victim's system when the file is loaded.

Affected products

• lightning-ai/pytorch-lightning: through 2.6.0

References

• https://github.com/Lightning-AI/pytorch-lightning
• https://www.notion.so/CVE-2026-31221-35d1e1393188815f8db7c4fd08076639

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