CVE-2026-87441 in Chrome
Summary
by MITRE • 09/09/2026
Missing authorization in Downloads in Google Chrome prior to 153.0.8010.36 allowed a remote attacker to bypass system access restrictions via a crafted Chrome extension. (Chromium security severity: Medium)
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Analysis
by VulDB Data Team • 09/09/2026
The vulnerability identified as missing authorization within the download functionality of Google Chrome versions prior to 153.0.8010.36 represents a critical failure in enforcing access control policies for file system interactions initiated by browser extensions. This flaw allows remote attackers, who can trick users into installing or interacting with maliciously crafted Chrome extensions, to bypass intended security restrictions that govern how and where files are saved on the host operating system. The core technical issue lies in the insufficient validation of permissions when an extension attempts to trigger a download operation through the browser's internal APIs. Normally, browsers enforce strict sandboxing and permission models to prevent web content or extensions from writing arbitrary data to sensitive locations without explicit user consent or elevated privileges. However, due to this authorization gap, the application fails to verify whether the requesting entity possesses the necessary rights to write to the target directory, effectively allowing unauthorized file system writes that circumvent standard security boundaries.
From a technical perspective, this vulnerability exploits the trust relationship between the browser engine and its extension ecosystem. Chrome extensions operate with varying levels of privilege depending on their declared permissions in the manifest file. While most operations are sandboxed, certain APIs allow for deeper integration with the host environment, including file system access. The flaw indicates that when an extension utilizes these privileged interfaces to initiate a download, the underlying security module does not adequately check if the specific action aligns with the extension's granted scope or if it violates local policy constraints designed to protect user data integrity and confidentiality. This oversight enables a remote attacker to craft an extension that appears benign but contains logic to write files to restricted directories such as system folders, application configuration paths, or other sensitive areas of the file system without triggering appropriate warnings or requiring additional authentication steps from the end-user.
The operational impact of this vulnerability is significant for both individual users and enterprise environments relying on Chrome for secure browsing and extension-based workflows. By bypassing access restrictions, an attacker can potentially plant malicious scripts, configuration files, or binaries in locations where they may be executed by other processes with higher privileges, leading to privilege escalation attacks. Furthermore, the ability to write arbitrary data to sensitive directories can facilitate persistence mechanisms, allowing malware to survive reboots and remain active even after initial detection attempts are cleared. In enterprise settings, this could lead to policy violations, unauthorized modification of critical system files, or the introduction of backdoors that compromise the integrity of the entire endpoint. The medium severity rating assigned by Chromium reflects the potential for exploitation but acknowledges that successful attacks typically require user interaction, such as installing a malicious extension, which acts as a mitigating factor against fully automated remote code execution scenarios.
To mitigate this risk, organizations and users must ensure that Google Chrome is updated to version 153.0.8010.36 or later, where the authorization checks for download operations have been hardened. It is crucial to enforce strict extension policies within enterprise environments using tools like Chrome Enterprise Policy Management to whitelist only approved extensions from trusted publishers and disable sideloading of unverified add-ons. Users should exercise caution when installing new extensions, reviewing their requested permissions carefully before granting access. Additionally, implementing endpoint detection and response solutions that monitor for unusual file system write activities originating from browser processes can provide an additional layer of defense against exploitation attempts. Regular security audits and adherence to the principle of least privilege in extension development practices are also essential long-term strategies to prevent similar authorization bypass vulnerabilities. This incident aligns with CWE-269, which describes Improper Privilege Management, highlighting the failure to enforce proper access control levels during critical operations within the application logic.