CVE-2026-118321 in Chrome
Summary
by MITRE • 10/28/2026
Improper input validation in Core in Google Chrome on on Android 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 Core component of Google Chrome on Android represents a significant breach in browser security boundaries, specifically affecting versions prior to 156.0.8078.73. This defect allows for remote code execution outside the confines of the standard sandbox environment, which is designed to isolate web content from the underlying operating system and user data. The root cause lies in insufficient checks performed on input data processed by the browser engine before it is executed or rendered. When a malicious actor crafts an HTML page containing specifically formatted inputs that bypass these validation routines, they can trigger undefined behavior within the memory management subsystems of the browser core. This failure to properly sanitize or validate incoming data streams creates a pathway for attackers to inject executable code into privileged contexts where normal security restrictions do not apply effectively.
From a technical perspective, this type of vulnerability typically manifests as a buffer overflow, use-after-free condition, or integer overflow within the rendering pipeline or JavaScript engine components that constitute the browser core. The Chromium project classifies such issues with high severity due to their potential for arbitrary code execution. When input validation is bypassed, an attacker can manipulate memory pointers or heap structures in ways that allow them to overwrite critical data or redirect program flow. This capability enables the injection of shellcode or other malicious payloads into processes running with elevated privileges relative to the sandboxed renderer process. The exploitation chain often involves convincing a user to visit a specially crafted webpage, which then leverages this validation flaw to escape the browser's security model and gain control over the underlying Android operating system components accessible to that application instance.
The operational impact of this vulnerability is severe, as it compromises the fundamental trust model of web browsing on mobile devices. By executing code outside the sandbox, an attacker can potentially access sensitive user data such as cookies, stored passwords, local storage contents, and device-specific identifiers without explicit permission from the operating system's runtime permissions framework. Furthermore, successful exploitation could allow for persistent malware installation, surveillance capabilities through camera or microphone access if those privileges were previously granted to Chrome, or lateral movement within a network if the compromised device is connected to corporate resources. The ability to execute arbitrary code means that traditional defenses like content security policies and same-origin policies are rendered ineffective once the sandbox boundary is breached, leaving the user's privacy and data integrity at significant risk.
Mitigation strategies primarily involve immediate software updates to ensure users are running version 156.0.8078.73 or later of Google Chrome on Android, where these input validation checks have been strengthened. For organizations managing fleets of devices, enforcing automatic update policies is critical to closing this window of exposure rapidly. In environments where immediate patching is not feasible, network-level controls such as web filtering proxies can be configured to block access to known malicious domains or detect patterns associated with exploit kits targeting browser vulnerabilities. Additionally, users should exercise caution when interacting with untrusted links and disable JavaScript execution for unknown sites if possible, although this significantly degrades user experience. Regular security audits of third-party extensions installed in the browser are also recommended, as they may attempt to leverage similar validation flaws or provide additional attack surfaces that compound the risk posed by core engine vulnerabilities.
This incident aligns with Common Weakness Enumeration (CWE) category CWE-20 Improper Input Validation and is often associated with ATT&CK technique T1059 Command and Scripting Interpreter, as well as T1203 Exploitation for Client Execution. The breach of sandbox boundaries corresponds to the privilege escalation aspects found in techniques like T1068 Exploitation for Privilege Escalation. Understanding these mappings helps security teams prioritize remediation efforts based on established threat intelligence frameworks and ensures that defensive measures are aligned with industry-standard classifications of vulnerability types and attack behaviors.