CVE-2026-87611 in Chrome
Summary
by MITRE • 09/09/2026
Missing authorization in FileSystem in Google Chrome prior to 153.0.8010.36 allowed a remote attacker who had compromised the renderer process to obtain cross-origin data 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 missing authorization within the FileSystem component of Google Chrome prior to version 153.0.8010.36 represents a significant breach in browser isolation mechanisms, specifically targeting the boundary between renderer processes and file system resources. This flaw allows an attacker who has already achieved code execution within a sandboxed renderer process to bypass intended access controls and retrieve sensitive data from cross-origin contexts. The core issue lies in the insufficient validation of authorization tokens or permissions when interacting with local file systems through web APIs, which undermines the fundamental security model that prevents malicious scripts on one origin from accessing resources belonging to another origin.
From a technical perspective, modern browsers employ multi-process architectures where each tab runs in an isolated renderer process to contain potential exploits. However, certain features such as the File System Access API or legacy file input mechanisms may expose interfaces that interact with the underlying operating system's file system without strictly enforcing cross-origin restrictions within the sandboxed environment. When a crafted HTML page is loaded by a victim user, it can exploit this gap in authorization logic to read files that should be inaccessible due to their origin mismatch. This effectively breaks the same-origin policy, which is critical for preventing data leakage between different web applications running on the same browser instance.
The operational impact of this vulnerability is severe because it facilitates cross-site scripting-like outcomes where sensitive user data can be exfiltrated without direct interaction beyond visiting a malicious site or being redirected to one. An attacker leveraging this flaw could potentially access local configuration files, cached credentials stored in file formats, or other private documents if the browser's sandboxing rules are not strictly enforced for these specific API calls. This capability significantly lowers the barrier for attackers who have compromised renderer processes through other vulnerabilities such as memory corruption bugs, allowing them to escalate their impact from mere code execution to data theft across domain boundaries.
In terms of industry standards and threat modeling, this vulnerability aligns with CWE-269, which describes Improper Authorization, where a user is able to access or modify data for which they should not have permissions. Furthermore, it relates to ATT&CK technique T1059, Command and Scripting Interpreter, as the renderer process compromise often serves as an initial foothold that this vulnerability helps expand into broader system access. The scenario also reflects aspects of T1005, Data from Local System, particularly when local files are targeted for exfiltration rather than network-based data sources.
Mitigation strategies primarily involve updating to a patched version of Google Chrome where the authorization checks within the FileSystem components have been strengthened to strictly enforce origin boundaries regardless of the process context. Administrators and users should ensure automatic updates are enabled to receive these security patches promptly. Additionally, defense-in-depth measures such as disabling unnecessary file system APIs in enterprise environments or using strict content security policies can reduce the attack surface available to renderer-based exploits. Regular auditing of browser configurations and limiting the privileges granted to web applications further mitigates the risk associated with such authorization bypasses.