Gradio is an open-source Python package designed for quick prototyping. Starting in version 4.16.0 and prior to version 6.6.0, Gradio applications running outside of Hugging Face Spaces automatically enable "mocked" OAuth routes when OAuth components (e.g. `gr.LoginButton`) are used. When a user visits `/login/huggingface`, the server retrieves its own Hugging Face access token via `huggingface_hub.get_token()` and stores it in the visitor's session cookie. If the application is network-accessible, any remote attacker can trigger this flow to steal the server owner's HF token. The session cookie is signed with a hardcoded secret derived from the string `"-v4"`, making the payload trivially decodable. Version 6.6.0 fixes the issue.
History

Fri, 27 Feb 2026 21:45:00 +0000

Type Values Removed Values Added
Description Gradio is an open-source Python package designed for quick prototyping. Starting in version 4.16.0 and prior to version 6.6.0, Gradio applications running outside of Hugging Face Spaces automatically enable "mocked" OAuth routes when OAuth components (e.g. `gr.LoginButton`) are used. When a user visits `/login/huggingface`, the server retrieves its own Hugging Face access token via `huggingface_hub.get_token()` and stores it in the visitor's session cookie. If the application is network-accessible, any remote attacker can trigger this flow to steal the server owner's HF token. The session cookie is signed with a hardcoded secret derived from the string `"-v4"`, making the payload trivially decodable. Version 6.6.0 fixes the issue.
Title Gradio: Mocked OAuth Login Exposes Server Credentials and Uses Hardcoded Session Secret
Weaknesses CWE-522
CWE-798
References
Metrics cvssV3_1

{'score': 0, 'vector': 'CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:N'}


cve-icon MITRE

Status: PUBLISHED

Assigner: GitHub_M

Published:

Updated: 2026-02-27T21:40:57.917Z

Reserved: 2026-02-18T00:18:53.963Z

Link: CVE-2026-27167

cve-icon Vulnrichment

No data.

cve-icon NVD

Status : Received

Published: 2026-02-27T22:16:22.820

Modified: 2026-02-27T22:16:22.820

Link: CVE-2026-27167

cve-icon Redhat

No data.