CVE-2026-118355 in Chrome
Summary
by MITRE • 10/28/2026
Improper input validation in Command in Google Chrome prior to 156.0.8078.73 allowed a remote attacker to potentially execute arbitrary code outside the sandbox via a crafted HTML page. (Chromium security severity: High)
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Analysis
by VulDB Data Team • 10/28/2026
The vulnerability identified as an improper input validation flaw within the command execution mechanisms of Google Chrome prior to version 156.0.8078.73 represents a critical breach in browser security boundaries. This defect allows for potential arbitrary code execution outside the confines of the sandbox, which is the primary defense mechanism designed to isolate web content from the underlying operating system. The severity of this issue is classified as high by Chromium standards, indicating that successful exploitation could lead to significant compromise of user systems without requiring local access or physical interaction beyond visiting a malicious webpage.
At its core, the technical flaw stems from insufficient validation and sanitization of inputs processed during command execution operations within the browser engine. When Chrome processes commands derived from web content, it relies on strict adherence to expected data formats and constraints. In this instance, the application failed to adequately verify or escape special characters, control sequences, or unexpected input structures before passing them to underlying system components or internal handlers. This lack of rigorous validation creates a pathway for attackers to inject malicious payloads that are interpreted as executable commands rather than benign data. The specific mechanism likely involves bypassing existing filters through crafted HTML pages that exploit edge cases in how the browser parses and executes certain script-based instructions or API calls linked to command execution contexts.
The operational impact of this vulnerability is severe due to its potential for remote code execution with elevated privileges relative to the sandboxed environment. A remote attacker can craft a malicious webpage containing specific HTML, JavaScript, or embedded objects designed to trigger the input validation failure. When an unsuspecting user visits this page, potentially through social engineering tactics such as phishing links or drive-by downloads, the browser processes the crafted content and executes arbitrary code outside the protective sandbox boundary. This escape from the sandbox allows the attacker to interact directly with the operating system, install malware, steal sensitive data, establish persistence mechanisms, or use the compromised machine for further attacks within a network. The ability to execute code remotely makes this vulnerability particularly dangerous as it does not require user interaction beyond initial page load in many scenarios.
This type of flaw is commonly categorized under CWE-20 Improper Input Validation and often relates to CWE-78 OS Command Injection when the execution context involves system-level commands. From a threat intelligence perspective, such vulnerabilities are frequently leveraged in campaigns aligned with MITRE ATT&CK techniques for initial access via spearphishing links or drive-by compromise, followed by defense evasion through sandbox escape tactics like T1608. The exploitation chain typically begins with delivering the malicious payload via web delivery and proceeds to privilege escalation within the browser context before achieving full system compromise.
Mitigation strategies primarily involve immediate patching of Google Chrome to version 156.0.8078.73 or later, where these input validation checks have been strengthened and corrected by Chromium developers. Organizations should enforce automatic update policies for all endpoints running this browser to ensure timely application of security fixes. Additionally, implementing network-level controls such as web filtering proxies can help block access to known malicious domains hosting exploit kits. Endpoint detection and response solutions should be configured to monitor for unusual process creation events originating from the Chrome executable, particularly those that attempt to spawn system shells or interact with sensitive API endpoints outside normal browser behavior patterns. User awareness training remains crucial to reduce the likelihood of users visiting untrusted sites where such crafted pages might reside.