Bug 2443454 (CVE-2026-27167)

Summary:	CVE-2026-27167 Gradio: Gradio: Information disclosure due to hardcoded secret in session cookie signing, allowing remote attackers to steal Hugging Face tokens.
Product:	[Other] Security Response	Reporter:	OSIDB Bzimport <bzimport>
Component:	vulnerability	Assignee:	Product Security DevOps Team <prodsec-dev>
Status:	NEW ---	QA Contact:
Severity:	low	Docs Contact:
Priority:	low
Version:	unspecified	CC:	jwong, omaciel, teagle, ttakamiy
Target Milestone:	---	Keywords:	Security
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Hardware:	All
OS:	Linux
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Doc Text:	A flaw was found in Gradio. When Gradio applications run outside of Hugging Face Spaces and use OAuth components, they automatically enable "mocked" OAuth routes. A remote attacker can exploit this by visiting the /login/huggingface endpoint, which causes the server to retrieve its Hugging Face (HF) access token and store it in the visitor's session cookie. Since the session cookie is signed with a hardcoded secret, the attacker can easily decode the payload and steal the server owner's HF token, leading to information disclosure.	Story Points:	---
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oVirt Team:	---	RHEL 7.3 requirements from Atomic Host:
Cloudforms Team:	---	Target Upstream Version:
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Description OSIDB Bzimport 2026-02-27 22:02:13 UTC

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.