{"id":"CVE-2026-31221","aliases":["GHSA-75m9-98v2-hjpm","PYSEC-2026-3043"],"url":"https://o3.security/vulnerability/CVE-2026-31221","summary":"PyTorch Lightning load_from_checkpoint has an insecure checkpoint deserialization","details":"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.","published":"2026-05-12T00:00:00Z","modified":"2026-08-07T11:31:07.467833915Z","cvss":{"score":8.8,"severity":"HIGH","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H"},"epss":null,"cisaKev":null,"exploitsKnown":0,"affectedPackages":[{"ecosystem":"PyPI","name":"pytorch-lightning","fixedVersion":null}],"fix":null,"references":[{"type":"WEB","url":"https://www.notion.so/CVE-2026-31221-35d1e1393188815f8db7c4fd08076639"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/31xxx/CVE-2026-31221.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-31221"},{"type":"PACKAGE","url":"https://github.com/Lightning-AI/pytorch-lightning"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-08-07T11:31:07.467833915Z"}}