CVE-2026-87515 in Chrome
Summary
by MITRE • 09/09/2026
Incorrect authorization in FileAPI in Google Chrome prior to 153.0.8010.36 allowed a remote attacker leveraging social engineering to bypass system access restrictions 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 FileAPI of Google Chrome prior to version 153.0.8010.36 represents a significant breach in browser-based access control mechanisms. This specific weakness allows for unauthorized data exfiltration by circumventing standard security boundaries that are designed to protect user privacy and system integrity. The core issue lies in the improper validation of permissions when web pages attempt to interact with local file systems through the FileAPI, which is intended to provide a secure interface for accessing files on a user's device while maintaining strict sandboxing rules.
The technical flaw stems from an inconsistency in how Chrome handles authorization checks during file access operations initiated by remote content. When a malicious actor crafts an HTML page designed to exploit this gap, they can trick the browser into granting elevated privileges or bypassing restrictions that should otherwise prevent such access. This typically involves manipulating the context in which the FileAPI is invoked, potentially exploiting race conditions or state management errors where the security token associated with the request does not correctly reflect the origin's permissions. By leveraging social engineering techniques, an attacker can persuade a user to visit this crafted page, thereby triggering the vulnerability without requiring any additional software installation or explicit user consent beyond normal browsing activities.
From an operational impact perspective, this vulnerability enables remote attackers to read sensitive files from the victim's system that should remain inaccessible to web content. Depending on the specific implementation details and the operating environment, this could lead to the disclosure of personal documents, configuration files containing credentials, or other proprietary data stored locally. The severity is classified as medium by Chromium security standards because while it does not allow for arbitrary code execution directly, the ability to exfiltrate local file system contents poses a substantial risk to user privacy and organizational data protection policies. It effectively breaks the web sandbox model that isolates untrusted content from the host operating system resources.
This type of vulnerability is commonly categorized under CWE-269, which refers to Improper Authorization, as it involves a failure in verifying whether an actor has the necessary permissions for a specific action. In terms of offensive security frameworks like MITRE ATT&CK, this behavior aligns with techniques related to Data from Local System Retrieval or potentially T1059 Command and Scripting Interpreter if combined with other exploits, though primarily it facilitates unauthorized data access consistent with reconnaissance or collection phases in an attack lifecycle. The reliance on social engineering highlights the importance of user awareness alongside technical controls, as the initial vector requires human interaction to initiate the exploit chain.
Mitigation strategies for this vulnerability are straightforward and center around timely software updates. Users must upgrade Google Chrome to version 153.0.8010.36 or later, where these authorization checks have been corrected to ensure that file access requests strictly adhere to origin-based permissions and sandbox boundaries. Additionally, organizations should enforce strict content security policies (CSP) within their browsers to limit the capabilities of web applications running in enterprise environments. Regular patch management cycles are essential to address such flaws promptly, as zero-day exploits for browser vulnerabilities often circulate rapidly among threat actors who monitor Chromium release notes for newly disclosed issues.