CVE-2026-118343 in Chrome
Summary
by MITRE • 10/28/2026
Improper input validation in ReadingList 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: High)
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Analysis
by VulDB Data Team • 10/28/2026
The vulnerability identified as an improper input validation flaw within the ReadingList component of Google Chrome prior to version 156.0.8078.73 represents a significant breach in the browser's defense-in-depth architecture. This specific defect allows for remote code execution, which is classified with high severity by the Chromium security team due to its potential to bypass sandbox restrictions and compromise system integrity. The core of the issue lies in how the ReadingList feature processes user-supplied data or content retrieved from external sources without sufficiently rigorous sanitization checks. When a victim visits a maliciously crafted HTML page, the browser's engine attempts to parse and render the content within the context of the reading list interface. Because the input validation logic fails to properly filter dangerous constructs or malformed structures, it permits the injection of executable code that is then interpreted by the JavaScript engine under elevated privileges relative to typical web content restrictions.
From a technical perspective, this vulnerability exploits weaknesses in how the browser handles complex HTML and script interactions within specific UI components like ReadingList. The sandbox mechanism designed to isolate untrusted web content from sensitive system resources relies on strict boundaries between different process types. However, improper input validation can lead to memory corruption or logic errors that allow an attacker to escape these isolation boundaries. By crafting a specially constructed HTML page containing malicious scripts and exploiting the parsing inconsistencies in the ReadingList module, an adversary can trigger arbitrary code execution within the sandboxed environment. This effectively neutralizes one of Chrome's primary security features, allowing the attacker to interact with underlying operating system resources that should remain inaccessible from standard web contexts.
The operational impact of this vulnerability is severe, as successful exploitation grants a remote attacker the ability to execute arbitrary commands on the victim’s machine. This can lead to full system compromise, including data theft, installation of persistent malware, or use of the device in botnets. Since the attack vector involves visiting a crafted web page, it falls under social engineering tactics where user interaction is required but often minimal, such as simply loading the page. The high severity rating reflects the ease with which this flaw can be weaponized and its potential to cause widespread damage across diverse environments running affected versions of Chrome.
To mitigate risks associated with this vulnerability, immediate action involves updating Google Chrome to version 156.0.8078.73 or later, where these input validation checks have been strengthened. Organizations should enforce automatic update policies for all endpoints using the browser to ensure timely patching against known exploits. Additionally, deploying web filtering solutions that block access to suspicious domains hosting malicious content can provide an additional layer of defense. Security teams should also monitor for indicators of compromise related to sandbox escape attempts and unusual process behaviors originating from Chrome processes.
This vulnerability aligns with CWE-20 Improper Input Validation, which describes failures in checking or transforming input data before processing it. It is further categorized under ATT&CK technique T1059 Command and Scripting Interpreter, as the exploitation involves executing code through interpreted languages like JavaScript within a constrained environment. Understanding these mappings helps security professionals prioritize remediation efforts based on established industry standards for vulnerability management and threat intelligence integration.