CVE-2026-121094 in Chrome
Summary
by MITRE • 11/03/2026
Type confusion in V8 in Google Chrome prior to 157.0.8103.38 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 • 11/03/2026
The vulnerability identified as a type confusion flaw within the V8 JavaScript engine, which powers Google Chrome prior to version 157.0.8103.38, represents a critical memory safety issue that undermines the browser's core execution model. Type confusions occur when an application incorrectly interprets the data type of a variable or object in memory, leading to operations being performed on data structures with incompatible types. In the context of V8, this typically involves misinterpreting JavaScript objects as different internal representations, such as confusing a heap-allocated object with a primitive value or vice versa. This discrepancy allows an attacker who crafts a malicious HTML page containing specific JavaScript payloads to manipulate how the engine handles memory references and data structures during execution.
From a technical perspective, the flaw exploits inconsistencies in V8's type inference system or its handling of polymorphic code paths. When the JIT compiler optimizes code based on assumed types, but those assumptions are violated by crafted input, the resulting machine code may perform invalid memory accesses or write to unintended locations. This can lead to arbitrary read and write primitives within the JavaScript heap space. The severity is classified as High because it provides a reliable pathway for escalating privileges from untrusted web content into more sensitive areas of the browser process.
The operational impact of this vulnerability is severe, enabling remote code execution inside the Chrome sandbox. Modern browsers rely heavily on sandboxing to isolate tab processes and restrict their access to system resources. However, if an attacker can achieve arbitrary code execution within the V8 engine's memory space, they may be able to exploit subsequent vulnerabilities or use browser-specific exploitation techniques such as heap spraying combined with ROP chains to break out of the sandbox boundary. This would allow full control over the user's machine, facilitating data theft, installation of malware, or further lateral movement in a networked environment.
This vulnerability aligns closely with CWE-843, which describes access to incorrect type via reference, and is often associated with CWE-120, buffer overflow, when it leads to memory corruption that facilitates code execution. In terms of the MITRE ATT&CK framework, this exploit falls under T1205.001, Trust Abuse: Complicit Third-Party Application, as it leverages a trusted component (the browser engine) to execute malicious actions. It also relates to T1059, Command and Scripting Interpreter, specifically through the abuse of JavaScript engines within web browsers.
Mitigation for this issue primarily involves updating Google Chrome to version 157.0.8103.38 or later, where these type confusion flaws have been patched by V8 developers. Organizations should ensure that automatic updates are enabled for all endpoints running affected versions of the browser. Additionally, security teams can implement content security policies and sandboxing configurations to limit the potential impact if a user inadvertently visits a malicious site. Monitoring network traffic for unusual outbound connections from browser processes may also help detect exploitation attempts in real-time before significant damage occurs.