CVE-2026-31221
PyTorch-Lightning Insecure Deserialization Vulnerability
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.
INFO
Published Date :
May 12, 2026, 4:16 p.m.
Last Modified :
May 15, 2026, 7:16 p.m.
Remotely Exploit :
Yes !
Source :
[email protected]
CVSS Scores
| Score | Version | Severity | Vector | Exploitability Score | Impact Score | Source |
|---|---|---|---|---|---|---|
| CVSS 3.1 | HIGH | [email protected] | ||||
| CVSS 3.1 | HIGH | 134c704f-9b21-4f2e-91b3-4a467353bcc0 |
Solution
- Update PyTorch-Lightning to a secure version.
- Ensure weights_only=True is used when loading checkpoints.
- Avoid loading untrusted checkpoint files.
- Review application checkpoint loading logic.
References to Advisories, Solutions, and Tools
Here, you will find a curated list of external links that provide in-depth
information, practical solutions, and valuable tools related to
CVE-2026-31221.
| URL | Resource |
|---|---|
| https://github.com/Lightning-AI/pytorch-lightning | Product |
| https://www.notion.so/CVE-2026-31221-35d1e1393188815f8db7c4fd08076639 | Exploit Third Party Advisory |
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2026-31221 is
associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification
(CAPEC)
stores attack patterns, which are descriptions of the common attributes and
approaches employed by adversaries to exploit the CVE-2026-31221
weaknesses.
We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).
Results are limited to the first 15 repositories due to potential performance issues.
The following list is the news that have been mention
CVE-2026-31221 vulnerability anywhere in the article.
The following table lists the changes that have been made to the
CVE-2026-31221 vulnerability over time.
Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.
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CVE Modified by 134c704f-9b21-4f2e-91b3-4a467353bcc0
May. 15, 2026
Action Type Old Value New Value Added CVSS V3.1 AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H Added CWE CWE-502 -
Initial Analysis by [email protected]
May. 14, 2026
Action Type Old Value New Value Added CVSS V3.1 AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H Added CWE CWE-502 Added CPE Configuration OR *cpe:2.3:a:lightningai:pytorch_lightning:*:*:*:*:*:python:*:* versions up to (including) 2.6.0 Added Reference Type MITRE: https://github.com/Lightning-AI/pytorch-lightning Types: Product Added Reference Type MITRE: https://www.notion.so/CVE-2026-31221-35d1e1393188815f8db7c4fd08076639 Types: Exploit, Third Party Advisory -
New CVE Received by [email protected]
May. 12, 2026
Action Type Old Value New Value Added 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. Added Reference https://github.com/Lightning-AI/pytorch-lightning Added Reference https://www.notion.so/CVE-2026-31221-35d1e1393188815f8db7c4fd08076639