CVE-2026-87510 in Chrome
Summary
by MITRE • 09/09/2026
Improper input validation in FileAPI in Google Chrome prior to 153.0.8010.36 allowed a remote attacker who had compromised the renderer process to potentially execute arbitrary code outside the sandbox 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 improper input validation flaw within the FileAPI component of Google Chrome prior to version 153.0.8010.36 represents a significant breach in browser isolation mechanisms. This defect specifically impacts the boundary between the renderer process and higher-privilege processes, allowing for potential sandbox escape scenarios. The core technical issue stems from insufficient sanitization or type checking of data inputs handled by the FileAPI interface when processing files selected via HTML forms or programmatically accessed through JavaScript. When a malicious actor crafts an HTML page designed to exploit this weakness, they can manipulate file metadata or content structures in ways that bypass expected validation logic within the browser engine.
From a technical perspective, the renderer process operates under strict sandboxing restrictions intended to limit its ability to interact with the underlying operating system directly. However, when input validation is improperly implemented, an attacker who has already achieved code execution within the compromised renderer can leverage this flaw to trigger undefined behavior or memory corruption in adjacent components that possess elevated privileges. By crafting specific file objects or manipulating the internal representation of file handles, the attacker can cause the browser to perform operations outside the intended security context. This effectively allows arbitrary code execution with higher privilege levels than those granted to standard web content, thereby breaking out of the sandbox environment.
The operational impact of this vulnerability is severe due to its potential for remote exploitation via a crafted HTML page. An attacker does not need physical access or prior authentication on the target system; instead, they can distribute malicious links through phishing campaigns, compromised websites, or other social engineering vectors. Once a victim visits the malicious site and interacts with the file upload mechanism or triggers specific JavaScript routines involving FileAPI calls, the vulnerability is activated. The successful exploitation leads to arbitrary code execution outside the sandbox, which typically grants the attacker full control over the user's system depending on the privileges of the browser process. This level of access enables data exfiltration, installation of persistent malware, and further lateral movement within a network if the compromised machine serves as an entry point.
This vulnerability aligns with CWE-20 Improper Input Validation in the Common Weakness Enumeration taxonomy, highlighting the failure to correctly verify or sanitize user-supplied input before processing it. Furthermore, from the perspective of the MITRE ATT&CK framework, this exploit technique relates to Defense Evasion and Privilege Escalation tactics, specifically those involving sandbox escape mechanisms such as process injection or API hooking that leverage browser vulnerabilities to gain unauthorized access. The Chromium security severity rating of Medium reflects the balance between the complexity required for exploitation and the high impact achieved upon success.
Mitigation strategies primarily involve updating Google Chrome to version 153.0.8010.36 or later, where these input validation checks have been hardened. For organizations unable to patch immediately due to compatibility concerns, implementing strict content security policies can help mitigate some risks by restricting the execution of inline scripts and limiting access to certain APIs. Additionally, deploying endpoint detection and response solutions that monitor for anomalous process creation patterns originating from browser processes can provide an additional layer of defense against sandbox escape attempts. Regularly auditing web applications for proper input handling practices remains essential to prevent similar vulnerabilities in custom implementations or extensions that interact with the FileAPI.