CVE-2026-101062

Received Received - Intake

OAuth Client Registration Bypass in Obot

Publication date: 2026-09-27

Last updated on: 2026-09-27

Assigner: VulnCheck

Description

Obot before v0.23.0 (affected versions <= v0.22.1) running with OBOT_SERVER_ENABLE_AUTHENTICATION=true exposes OAuth dynamic client registration without authentication and without any restriction on the redirect URIs a client may register. Because the authorization flow auto-completes for an already logged-in user with no consent screen, an attacker who registers a client pointing at their own domain and induces a logged-in victim to visit a single crafted authorization URL receives an authorization code at the attacker-controlled redirect URI and can exchange it for an access token and refresh token. The token minted by the MCP OAuth flow carries the victim's full group set in the JWT, and Obot validated only the issuer and not the audience, so the token is accepted as a bearer token against any Obot API endpoint the victim can access rather than being scoped to the requested MCP server, allowing the attacker to read or modify the victim's resources until the token is revoked. v0.23.0 adds a consent screen, restricts MCP OAuth tokens to the MCP involved in the request, and enforces audience validation.

CVSS Scores

EPSS Scores

Probability:
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Meta Information

Published

2026-09-27

Last Modified

2026-09-27

Generated

2026-09-28

AI Q&A

2026-09-28

EPSS Evaluated

N/A

NVD

CVE-2026-101062

Affected Vendors & Products

Vendor	Product	Version / Range
obot	obot	to 0.23.0 (exc)

Helpful Resources

Exploitability

CWE

KEV

CWE ID	Description
CWE-863	The product performs an authorization check when an actor attempts to access a resource or perform an action, but it does not correctly perform the check.

Attack-Flow Graph

Executive Summary

Obot versions before v0.23.0 with OBOT_SERVER_ENABLE_AUTHENTICATION=true allow unauthenticated OAuth dynamic client registration. Attackers can register malicious clients with arbitrary redirect URIs. When a logged-in victim visits a crafted authorization URL, the attacker receives an authorization code and exchanges it for tokens. These tokens carry the victim's group permissions and are not properly scoped, allowing access to any Obot API endpoint the victim can access.

Impact Analysis

If you use Obot versions <= v0.22.1 with authentication enabled, an attacker could gain unauthorized access to your Obot resources. They could read or modify your data, perform actions on your behalf, and maintain access until tokens are revoked. The impact includes data breaches, unauthorized modifications, and potential lateral movement within your systems.

Compliance Impact

This vulnerability could lead to unauthorized access to sensitive data, violating confidentiality requirements in GDPR and HIPAA. The lack of proper token scoping and audience validation may result in non-compliance with data protection principles, potentially leading to regulatory fines and reputational damage.

Mitigation Strategies

Upgrade Obot to version v0.23.0 or later to address the OAuth dynamic client registration and token validation issues. Ensure the consent screen is enforced and MCP OAuth tokens are restricted to the MCP involved in the request.

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