CVE-2026-31221
Description
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.
Statement
This is an Important arbitrary code execution flaw in PyTorch-Lightning due to insecure deserialization in its checkpoint loading mechanism. Red Hat products utilizing PyTorch-Lightning, such as Red Hat Enterprise Linux AI and Red Hat AI Inference Server, are affected if they process untrusted checkpoint files. An attacker can craft a malicious checkpoint file, which, when loaded, can lead to arbitrary code execution on the system.
Mitigation
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.
Common Vulnerability Scoring System (CVSS) Score Details
Info alert:Important note
CVSS scores for open source components depend on vendor-specific factors (e.g. version or build chain). Therefore, Red Hat's score and impact rating can be different from NVD and other vendors. Red Hat remains the authoritative CVE Naming Authority (CNA) source for its products and services (see Red Hat classifications).
The following CVSS metrics and score provided are preliminary and subject to review.
CVSS v3 Score Breakdown
| Red Hat | NVD | cve.org | |
|---|---|---|---|
| Base Score | 8 | 7.8 | 8.8 |
| Attack Vector | Network | Local | Network |
| Attack Complexity | Low | Low | Low |
| Privileges Required | Low | None | None |
| User Interaction | Required | Required | Required |
| Scope | Unchanged | Unchanged | Unchanged |
| Confidentiality | High | High | High |
| Integrity Impact | High | High | High |
| Availability Impact | High | High | High |
Vector
Red Hat: CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:H/I:H/A:H
NVD: CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
cve.org: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
Understanding the Weakness (CWE)
Integrity
Technical Impact: Modify Application Data; Unexpected State
Attackers can modify unexpected objects or data that was assumed to be safe from modification. Deserialized data or code could be modified without using the provided accessor functions, or unexpected functions could be invoked.
Availability
Technical Impact: DoS: Resource Consumption (CPU)
If a function is making an assumption on when to terminate, based on a sentry in a string, it could easily never terminate.
Other
Technical Impact: Varies by Context
The consequences can vary widely, because it depends on which objects or methods are being deserialized, and how they are used. Making an assumption that the code in the deserialized object is valid is dangerous and can enable exploitation. One example is attackers using gadget chains to perform unauthorized actions, such as generating a shell.
Frequently Asked Questions
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