CVE-2026-118331 in Chrome
Summary
by MITRE • 10/28/2026
Improper input validation in FileAPI in Google Chrome prior to 156.0.8078.73 allowed a remote attacker to potentially execute arbitrary code inside the sandbox via a crafted HTML page. (Chromium security severity: Critical)
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Analysis
by VulDB Data Team • 10/28/2026
The vulnerability identified as an improper input validation flaw within the FileAPI component of Google Chrome prior to version 156.0.8078.73 represents a significant breach in browser security boundaries. This defect allows a remote attacker, through the delivery of a specially crafted HTML page, to potentially execute arbitrary code within the context of the browser sandbox. The severity is classified as Critical by Chromium standards, indicating that successful exploitation could lead to full system compromise if additional conditions are met or if the sandbox escape is achieved.
At its core, this vulnerability stems from insufficient validation checks performed on data inputs processed by the FileAPI interface. When a user visits a malicious webpage containing crafted HTML and associated scripts, the browser attempts to process file-related operations such as reading metadata, handling file paths, or managing blob objects. The flaw lies in how these inputs are parsed and validated before being passed to lower-level system calls or internal rendering engines. Specifically, the application fails to adequately sanitize or verify the structure and content of specific input parameters, allowing an attacker to inject malformed data that triggers unexpected behavior within the memory management subsystems.
The operational impact of this vulnerability is severe due to its potential for remote code execution. An attacker can host a malicious website designed to exploit this flaw when targeted users visit it. By leveraging the improper validation in FileAPI, the attacker constructs an attack vector that manipulates how files are handled internally. If successful, this manipulation allows the injection and execution of arbitrary commands or payloads inside the browser sandbox. While modern browsers employ robust sandboxing mechanisms to isolate web content from the host operating system, vulnerabilities like this often serve as a stepping stone for sandbox escapes. Once code execution is achieved within the sandbox, further exploitation techniques may be employed to break out into the broader user context or even the kernel level, depending on the specific implementation details and patch status of the underlying OS components.
This type of vulnerability aligns with Common Weakness Enumeration category CWE-20, which defines Improper Input Validation. It also maps closely to MITRE ATT&CK techniques related to Initial Access via Spearphishing Link or Drive-by Compromise, where a victim is tricked into visiting a malicious site that exploits browser vulnerabilities without requiring user interaction beyond navigation. The attack vector is classified as Network-based and Remote, meaning no physical access or local authentication is required for the initial exploitation phase.
Mitigation strategies primarily involve immediate software updates to ensure all instances of Google Chrome are upgraded to version 156.0.8078.73 or later, where these input validation checks have been corrected by developers. Organizations should enforce automated patch management policies to minimize exposure windows for such critical vulnerabilities. Additionally, users can employ browser hardening techniques such as disabling JavaScript execution on untrusted sites using extensions like NoScript, although this may impact usability. Security teams should also monitor network traffic for unusual outbound connections following visits to suspicious websites, as these could indicate successful exploitation attempts. Regular vulnerability scanning and penetration testing of web-facing assets help identify if any internal systems are serving malicious content that might target outdated browser versions within the enterprise environment.