CVE-2026-87508 in Chrome
Summary
by MITRE • 09/09/2026
Incorrect authorization in Loader in Google Chrome prior to 153.0.8010.36 allowed a remote attacker to bypass web origin policy via a crafted HTML page. (Chromium security severity: Medium)
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Analysis
by VulDB Data Team • 09/09/2026
The vulnerability identified as an incorrect authorization flaw within the loader component of Google Chrome, specifically affecting versions prior to 153.0.8010.36, represents a significant breach in web origin policy enforcement. This issue stems from a logic error or misconfiguration within the browser's internal mechanisms responsible for handling resource loading and cross-origin requests. In modern web browsers, the same-origin policy is a critical security model that restricts how documents or scripts loaded from one origin can interact with resources from another origin. The loader component plays a pivotal role in this process by managing network requests and ensuring that data retrieved from external sources adheres to these strict isolation boundaries. When authorization checks are incorrectly implemented, the browser fails to properly validate whether a requesting script has legitimate permission to access specific cross-origin resources, thereby allowing unauthorized data exfiltration or manipulation.
From a technical perspective, this flaw allows a remote attacker to craft an HTML page that exploits the misconfigured loader logic. By leveraging carefully constructed web pages, an adversary can trigger requests that bypass standard origin checks. This typically involves manipulating headers, cookies, or specific API calls in a way that tricks the browser into treating a cross-origin request as if it were same-origin. The attacker does not need to exploit complex memory corruption bugs but rather relies on logical errors in how permissions are evaluated during the loading phase of web content. Because this occurs at the application layer within the browser engine, it bypasses traditional network-level security controls and exploits the trust relationship between the user's session and the website they are visiting.
The operational impact of this vulnerability is substantial for users relying on Chrome for sensitive activities such as online banking, email access, or corporate portal usage. An attacker who successfully exploits this flaw can read sensitive data from other websites that a victim has authenticated sessions with, provided those sites do not implement additional protective measures like strict Content Security Policy headers or proper CORS configurations. This effectively breaks the isolation between different web applications running in the same browser instance. The consequences include potential account takeover through session hijacking, unauthorized access to personal information such as addresses and financial details, and the ability to perform actions on behalf of the user without their consent. Given that Chrome is one of the most widely used browsers globally, this vulnerability poses a widespread risk to internet users worldwide.
In terms of industry standards, this type of flaw aligns with CWE-269, which describes Improper Authorization, where an actor is able to access or modify data for which they should not have permission. It also relates closely to CWE-359, the Exposure of Private Information to an Unauthorized Actor, as the primary goal is often to steal sensitive user data. From a threat intelligence perspective, this behavior maps to MITRE ATT&CK technique T1078, Valid Accounts, specifically in the context of session hijacking or impersonation through browser-based attacks. It also falls under the broader category of client-side code injection and cross-site scripting variants that aim to bypass security policies rather than inject malicious scripts directly into a page's DOM.
Mitigation for this vulnerability primarily involves updating Google Chrome to version 153.0.8010.36 or later, where these authorization checks have been corrected by the Chromium development team. For organizations managing large fleets of devices, deploying automated patch management solutions is essential to ensure timely remediation across all endpoints. Additionally, web developers should reinforce their applications with robust security headers such as Content Security Policy (CSP) and Strict-Transport-Security (HSTS). These measures provide defense-in-depth by restricting the types of resources that can be loaded and ensuring connections are encrypted, thereby reducing the attack surface even if a browser-level vulnerability is present. Users should also exercise caution when visiting untrusted websites and consider using privacy-focused extensions or sandboxing techniques to limit the potential impact of such exploits on their personal data.