CVE-2026-113231 in Chrome
Summary
by MITRE • 10/21/2026
Improper input validation in Extensions in Google Chrome prior to 156.0.8078.47 allowed a remote attacker to potentially execute arbitrary code inside the sandbox via a crafted HTML page. (Chromium security severity: Medium)
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Analysis
by VulDB Data Team • 10/21/2026
The vulnerability identified as an improper input validation flaw within the Extensions component of Google Chrome prior to version 156.0.8078.47 represents a significant breach in the browser's defense-in-depth architecture. This specific defect allows for potential arbitrary code execution inside the sandbox, which is a critical security boundary designed to isolate untrusted content from sensitive system resources. The root cause lies in insufficient sanitization or type-checking of data inputs processed by extension APIs, enabling an attacker to craft malicious HTML pages that exploit these validation gaps. When such a page is rendered and executed within the browser environment, it can trigger unintended behavior in the underlying Chromium engine components responsible for managing extensions, thereby bypassing expected security constraints.
From a technical perspective, this flaw aligns with CWE-20 Improper Input Validation, where software fails to verify that user-supplied input conforms to expected formats, types, or ranges before processing. In the context of browser extensions, which often possess elevated privileges compared to standard web content, such validation failures are particularly dangerous. The attacker leverages a crafted HTML page containing specially constructed scripts or object tags designed to trigger specific extension behaviors. By exploiting the lack of rigorous input checking, the malicious payload can manipulate internal state variables or invoke functions in an unexpected manner. This manipulation facilitates code execution within the sandboxed environment, effectively neutralizing one of the primary security mechanisms intended to contain damage from compromised web content.
The operational impact of this vulnerability is severe due to its potential for remote exploitation without user interaction beyond visiting a malicious site. An attacker can host the crafted HTML page on a server and lure victims through phishing campaigns or drive-by downloads. Once executed, the arbitrary code runs within the sandbox, which while restrictive, still provides access to certain browser features such as local storage, cookies, and potentially sensitive data accessible by extensions with broad permissions. If an extension has been granted high-level privileges like accessing all website data or managing bookmarks, the compromised context could lead to credential theft, session hijacking, or further lateral movement within the user's digital environment. The Chromium security severity rating of Medium reflects that while exploitation requires specific conditions and may be mitigated by other browser protections, the underlying risk remains substantial for users with vulnerable versions installed.
This incident is also relevant to MITRE ATT&CK techniques related to client-side execution and sandbox escape attempts. Specifically, it relates to T1059 Command and Scripting Interpreter, where attackers use scripts to execute commands within a compromised environment. The ability to execute code inside the sandbox indicates that the attacker has achieved initial access via web content but is attempting to expand their foothold by leveraging extension APIs. This highlights the importance of strict input validation not just at the application boundary but also within internal components like extensions, which are often treated as more trusted entities than standard tabs.
To mitigate this risk, users must immediately update Google Chrome to version 156.0.8078.47 or later, where these input validation checks have been strengthened and patched by the Chromium team. Administrators should enforce automatic updates for all endpoints within their organizations to ensure consistent protection against such vulnerabilities. Additionally, security teams should audit installed extensions for necessity and revoke permissions that are not strictly required for core functionality, thereby reducing the attack surface available to an attacker who might exploit this flaw. Implementing Content Security Policy headers where applicable can also help restrict inline script execution, adding another layer of defense against crafted HTML pages designed to trigger such vulnerabilities. Regular monitoring of browser security advisories and maintaining up-to-date software configurations are essential practices for minimizing exposure to these types of input validation defects in modern web browsers.