CVE-2026-78938 in Chrome
Summary
by MITRE • 08/26/2026
Type confusion in V8 in Google Chrome prior to 152.0.7977.65 allowed a remote attacker to execute arbitrary code inside the sandbox via a crafted HTML page. (Chromium security severity: High)
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Analysis
by VulDB Data Team • 08/26/2026
The vulnerability identified as a type confusion flaw within the V8 JavaScript engine, which powers Google Chrome prior to version 152.0.7977.65, represents a critical failure in memory safety and runtime type checking mechanisms. Type confusion vulnerabilities occur when an application incorrectly assumes that a variable or object is of one data type while it actually contains another. In the context of V8, this typically involves the engine misinterpreting the structure or properties of JavaScript objects during execution. When a crafted HTML page triggers this condition, the browser's sandboxing mechanisms are bypassed because the attacker can manipulate memory layouts to gain unauthorized access to sensitive areas of the process space that should remain isolated from untrusted web content.
From a technical perspective, V8 relies on hidden classes and optimized code paths to ensure high performance in JavaScript execution. These optimizations assume strict adherence to type consistency throughout an object's lifecycle. When this assumption is violated due to a logic error or insufficient validation during property access or method invocation, the engine may execute instructions based on incorrect memory offsets or data interpretations. This discrepancy allows an attacker to perform out-of-bounds reads and writes, effectively breaking the isolation boundaries that protect the browser from malicious scripts. The severity of this issue is classified as High by Chromium security standards because it directly facilitates arbitrary code execution within the sandboxed environment, which is a primary defense layer against web-based attacks.
The operational impact of exploiting this vulnerability is severe, enabling remote attackers to execute arbitrary commands on the victim's system with the privileges of the browser process. This can lead to full system compromise if additional vulnerabilities are chained or if the user has elevated permissions. Attackers could install malware, steal sensitive data such as cookies and session tokens, or use the compromised machine for further attacks in a botnet. The ability to execute code inside the sandbox significantly lowers the barrier for exploitation compared to out-of-sandbox exploits, making this vulnerability particularly dangerous in widespread deployment scenarios where users frequently visit untrusted websites.
This flaw aligns with Common Weakness Enumeration (CWE) category CWE-843, which covers Access of Resource Using Incompatible Type Constraints. It also maps closely to MITRE ATT&CK techniques related to client-side code execution and sandbox escape, specifically those involving memory corruption or type confusion attacks that leverage browser engine vulnerabilities. The exploitation vector is classified as remote via the network with an attack complexity of low for skilled attackers who can craft specific HTML payloads designed to trigger the type confusion state within V8's optimization pipelines.
Mitigation strategies primarily involve updating Google Chrome and its underlying Chromium components to version 152.0.7977.65 or later, where these memory safety issues have been addressed through rigorous code reviews and automated fuzzing tests that detect such inconsistencies before release. For organizations unable to update immediately, deploying network-level controls such as web application firewalls with advanced threat protection capabilities can help block known exploit patterns associated with this vulnerability. Additionally, enabling sandbox enforcement features and restricting the execution of untrusted scripts through strict content security policies can reduce the attack surface available to potential adversaries attempting to leverage this type confusion flaw for malicious purposes.