pytorch-lightning: PyTorch-Lightning: Arbitrary code execution via insecure deserialization of checkpoint files (CVE-2026-31221)

Overview

A flaw was found in PyTorch-Lightning. This vulnerability, categorized as insecure deserialization (CWE-502), exists in the checkpoint loading mechanism. A remote attacker can exploit this by providing a maliciously crafted checkpoint file, which, when loaded by the LightningModule.load_from_checkpoint() method, allows the deserialization of arbitrary Python objects. This can lead to arbitrary code execution on the victim's system.

Vendor advisories

• Red Hat VEX · Important · affected: Red Hat AI Inference Server, Red Hat Enterprise Linux AI (RHEL AI) 3, Red Hat OpenShift AI (RHOAI) · no fix planned: Red Hat AI Inference Server, Red Hat OpenShift AI (RHOAI), Red Hat Enterprise Linux AI (RHEL AI) 3 · updated 2026-09-24 · vex

pytorch-lightning: PyTorch-Lightning: Arbitrary code execution via insecure deserialization of checkpoint files — rated Important by Red Hat. Released 2026-05-12, updated 2026-09-24.

Affected:

• Red Hat AI Inference Server
• Red Hat Enterprise Linux AI (RHEL AI) 3
• Red Hat OpenShift AI (RHOAI)

No fix planned:

• Red Hat AI Inference Server
• Red Hat OpenShift AI (RHOAI)
• Red Hat Enterprise Linux AI (RHEL AI) 3

Remediation

Will not fix

Workarounds / mitigations:

• To mitigate this issue, avoid loading PyTorch-Lightning checkpoint files from untrusted or unverified sources. Ensure that all checkpoint files originate from trusted environments to prevent the deserialization of malicious Python objects and subsequent arbitrary code execution.

Package advisory (CVE-2026-31221)

Affected packages:

• pytorch-lightning <= 2.6.0

Source: https://osv.dev/vulnerability/GHSA-75m9-98v2-hjpm