CVE-2026-97288 in OAuth Server Plugin
Summary
by MITRE • 09/30/2026
Contributor Cross Site Scripting (XSS) in OAuth Server <= 4.5.1 versions.
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Analysis
by VulDB Data Team • 09/30/2026
The vulnerability identified as Contributor Cross-Site Scripting within the OAuth Server, specifically affecting versions up to and including 4.5.1, represents a significant security flaw rooted in inadequate input validation and output encoding mechanisms. This type of weakness allows an attacker to inject malicious client-side scripts into web pages viewed by other users. In the context of an OAuth server, which is responsible for authorizing access to protected resources on behalf of a user, such a vulnerability can have severe consequences beyond typical cross-site scripting scenarios because it compromises the integrity and trust model of the authentication flow itself. The flaw typically arises when the application accepts unsanitized input from contributors or users—such as display names, profile information, or callback parameters—and reflects this data back into the HTML response without proper encoding. This failure aligns directly with CWE-79, which classifies improper neutralization of input during web page generation, commonly known as Cross-Site Scripting.
From a technical perspective, the exploitation of this vulnerability requires an attacker to craft a malicious payload that is embedded within data fields processed by the OAuth server. When another user interacts with the compromised interface or views content influenced by the injected script, their browser executes the arbitrary JavaScript code in the context of the application's domain. This execution environment grants the malicious script access to sensitive cookies, session tokens, and local storage items associated with the authenticated session. Because the vulnerability exists within an OAuth server, successful exploitation could allow an attacker to hijack user sessions, steal authorization codes or access tokens, or perform actions on behalf of the victim without their knowledge. This undermines the fundamental principle of least privilege and confidentiality that OAuth protocols are designed to enforce.
The operational impact of this vulnerability is substantial, particularly in environments where multiple contributors or third-party applications interact with the central identity provider. An attacker could use the injected script to exfiltrate sensitive authentication artifacts, such as access tokens or refresh tokens, which provide long-term access to user accounts and associated resources. Furthermore, if the OAuth server manages contributor roles or permissions, an attacker might manipulate these settings by forging requests that appear legitimate due to the stolen session context. This could lead to unauthorized elevation of privileges, where a low-privileged contributor gains administrative control over applications or users managed through the platform. The attack vector is generally classified as remote and non-persistent if the payload is not stored in a database but rather reflected immediately, though it can become persistent if user-supplied data containing the script is saved to server-side storage for later retrieval by other users.
In terms of industry frameworks, this vulnerability maps closely to MITRE ATT&CK technique T1059, specifically sub-technique 007 which covers JavaScript execution in web browsers. The exploitation strategy often involves social engineering or phishing tactics where a victim is lured into clicking a link containing the malicious payload embedded within OAuth parameters like redirect URIs or profile fields. This aligns with ATT&CK tactic TA0001, Initial Access, as gaining control over an authenticated session can serve as a foothold for further lateral movement within the organization's infrastructure. Additionally, if the stolen tokens are used to access downstream services, it relates to T1528, Steal Application Access Token, highlighting the critical nature of protecting these credentials during both transmission and storage phases.
Mitigation strategies must focus on rigorous input validation and robust output encoding practices across all components of the OAuth server architecture. Developers should implement strict allow-listing for any user-controlled data that is rendered in HTML contexts, ensuring that only expected characters are accepted. It is crucial to apply context-sensitive encoding when inserting dynamic content into web pages; this includes using HTML entity encoding for text nodes and URL encoding for query parameters or fragment identifiers. Furthermore, the implementation of Content Security Policy headers can significantly reduce the impact of any successful XSS attack by restricting the sources from which scripts can be loaded and executed. Upgrading to a version of the OAuth server greater than 4.5.1 is the primary remediation step, as newer releases likely include patches for these input handling deficiencies. Regular security audits and static code analysis tools configured to detect CWE-79 patterns should also be integrated into the development lifecycle to prevent similar vulnerabilities from being introduced in future updates.