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Vulnerability record · CVE-2026-31221 · published 12 May 2026

CVE-2026-31221: Lightningai pytorch lightning deserialization of untrusted data vulnerability

Lightningai · Pytorch Lightning

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.

7.8 CVSS 3.1 High EPSS 0.55% · top 56.0% CWE-502 · Deserialization of untrusted data
7.8CVSS 3.1 base score
0.55%EPSS exploitation probability, 30 days
NoNot in CISA KEV
1Affected product versions listed by NVD
2References, 1 tagged exploit
17 Jun 2026Last modified by NVD

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.

CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H

Affected products

1 vulnerable configurations from NVD's CPE data, grouped by vendor and product.

References

LinkTags
https://github.com/Lightning-AI/pytorch-lightning Product
https://www.notion.so/CVE-2026-31221-35d1e1393188815f8db7c4fd08076639 ExploitThird Party Advisory

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Source: NIST National Vulnerability Database (record CVE-2026-31221), CISA KEV, FIRST EPSS (scores of 2026-09-26). This page is refreshed as NVD updates the record.