# CVE-2026-40086: danielgatis rembg path traversal in HTTP server custom model loading

Source: https://junglewise.ai/threats/cve-2026-40086-danielgatis-rembg-path-traversal-in-http-server-custom-model  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-04-10. Updated: 2026-05-10  
License: CC BY 4.0 with a link back

CVE-2026-40086 · Severity: medium · CVSS 5.3 · Published 2026-04-10

Rembg is a tool used to remove backgrounds from images. A security flaw in its HTTP server mode allows an attacker to trick the system into trying to load any file on the server as a machine learning model. This can be used to confirm the existence of sensitive files, check system permissions, or potentially crash the service by attempting to load extremely large files.

Technologies: [Danielgatis Rembg](https://junglewise.ai/threats/technologies/rembg), [rembg (PyPI)](https://junglewise.ai/threats/technologies/pypi-rembg). Vendors: [Danielgatis](https://junglewise.ai/threats/vendors/danielgatis), [PyPI](https://junglewise.ai/threats/vendors/pypi).

## Quick answers

**Is CVE-2026-40086 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-40086 being exploited in the wild.

**How severe is CVE-2026-40086?** Medium severity, with a CVSS score of 5.3, published 10 April 2026.

**Which products and versions are affected?** Danielgatis Rembg < 2.0.75; rembg (PyPI) ECOSYSTEM:introduced=0,fixed=2.0.75.

**Is there a fix for CVE-2026-40086?** Yes. rembg (PyPI): upgrade to 2.0.75 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-40086 attacked?** It is attacked over the network, in a software library.

**Am I affected by CVE-2026-40086?** Check whether you run Danielgatis Rembg or rembg (PyPI) at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## How to fix

- rembg (PyPI): upgrade to 2.0.75 or later

  ```sh
  pip install "rembg>=2.0.75"
  ```


## Technical details

A path traversal vulnerability exists in the rembg HTTP server when handling custom model types (u2net_custom, dis_custom, ben_custom). The 'extras' JSON parameter is parsed without validation in 'rembg/commands/s_command.py' and passed to 'new_session()'. The 'model_path' within these extras is then processed by 'os.path.abspath' and 'os.path.expanduser' without being restricted to a safe directory. Finally, 'onnxruntime.InferenceSession' attempts to load the file at the attacker-provided path. While the file is not returned directly, error messages from the ONNX runtime reveal whether a file exists, its accessibility, and whether it was successfully read, enabling file enumeration and information disclosure. This is patched in version 2.0.75.

## Affected products

- danielgatis rembg < 2.0.75

## Identifiers

- CVE-2026-40086
- GHSA-3wqj-33cg-xc48
- PYSEC-2026-2274

## Timeline

- 2026-04-09: disclosed
- 2026-04-10: advisory
- 2026-04-10: patched: Fixed in version 2.0.75

## References

- [https://api.github.com/users/yueyueL](https://api.github.com/users/yueyueL)
- [https://github.com/yueyueL](https://github.com/yueyueL)
- [https://api.github.com/users/yueyueL/gists%7B/gist_id%7D](https://api.github.com/users/yueyueL/gists%7B/gist_id%7D)
- [https://api.github.com/users/yueyueL/repos](https://api.github.com/users/yueyueL/repos)
- [https://avatars.githubusercontent.com/u/64764840?v=4](https://avatars.githubusercontent.com/u/64764840?v=4)
- [https://api.github.com/users/yueyueL/events%7B/privacy%7D](https://api.github.com/users/yueyueL/events%7B/privacy%7D)

## Related threats

- [Rembg path traversal and file disclosure via sam_model parameter](https://junglewise.ai/threats/cve-2026-115924-rembg-is-a-tool-to-remove-images-background-prior-to-2-0-82-the)
- [danielgatis rembg SSRF and CORS misconfiguration in HTTP server](https://junglewise.ai/threats/danielgatis-rembg-ssrf-and-cors-misconfiguration-in-http-server-1965b168)
- [Rembg allows SSRF via /api/remove](https://junglewise.ai/threats/cve-2025-25301-rembg-allows-ssrf-via-api-remove)
- [Rembg CORS misconfiguration](https://junglewise.ai/threats/cve-2025-25302-rembg-cors-misconfiguration)