CVE-2026-43886
Received Received - Intake
OAuth Scope Validation Bypass in Outline

Publication date: 2026-05-11

Last updated on: 2026-05-11

Assigner: GitHub, Inc.

Description
Outline is a service that allows for collaborative documentation. From 0.84.0 to 1.6.1, a logic error in OAuthInterface.validateScope() uses Array.some() to validate requested OAuth scopes, causing the function to accept the entire scope array if any single scope is valid. An attacker can smuggle the wildcard * scope by requesting scope=read *, escalating a read-only OAuth token to full unrestricted API access including write, delete, and admin operations. This vulnerability is fixed in 1.7.0.
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Meta Information
Published
2026-05-11
Last Modified
2026-05-11
Generated
2026-06-21
AI Q&A
2026-05-12
EPSS Evaluated
2026-06-20
NVD
CVE-2026-43886
Affected Vendors & Products
Showing 2 associated CPEs
Vendor Product Version / Range
outline outline From 0.84.0 (inc) to 1.6.1 (inc)
outline outline 1.7.0
Helpful Resources
Exploitability
CWE
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KEV
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CWE ID Description
CWE-269 The product does not properly assign, modify, track, or check privileges for an actor, creating an unintended sphere of control for that actor.
Attack-Flow Graph
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Compliance Impact

This vulnerability allows an attacker to escalate a read-only OAuth token to full unrestricted API access, including write, delete, and admin operations. Such unauthorized access and potential data manipulation could lead to violations of data protection and privacy regulations like GDPR and HIPAA, which require strict controls over access to sensitive data.

Specifically, the escalation of privileges could result in unauthorized disclosure, alteration, or deletion of personal or protected health information, thereby compromising confidentiality and integrity requirements mandated by these standards.

Executive Summary

This vulnerability exists in the Outline service versions 0.84.0 to 1.6.1. It is caused by a logic error in the OAuthInterface.validateScope() function, which uses Array.some() to validate requested OAuth scopes. Due to this error, if any single scope in the requested scope array is valid, the function incorrectly accepts the entire scope array.

An attacker can exploit this by including the wildcard * scope in their request (for example, scope=read *), which allows them to escalate a read-only OAuth token to have full unrestricted API access. This includes permissions to write, delete, and perform admin operations. The issue was fixed in version 1.7.0.

Impact Analysis

This vulnerability can have serious security impacts. An attacker who exploits it can escalate their OAuth token privileges from read-only to full unrestricted access. This means they could potentially modify, delete, or administer data and resources within the Outline service without authorization.

Such unauthorized access could lead to data breaches, loss of data integrity, unauthorized changes, and disruption of service.

Mitigation Strategies

The vulnerability is fixed in Outline version 1.7.0. To mitigate this vulnerability, you should upgrade your Outline service to version 1.7.0 or later.

Until the upgrade is applied, be cautious with OAuth tokens that request scopes containing wildcards, as they may allow escalation from read-only to full unrestricted API access.

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