CVE-2026-121173 in Chrome
Summary
by MITRE • 11/03/2026
Uninitialized resource in WebGL in Google Chrome prior to 157.0.8103.38 allowed a remote attacker to read memory outside 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 an uninitialized resource issue within the WebGL subsystem of Google Chrome, specifically affecting versions prior to 157.0.8103.38, represents a critical failure in memory management and state initialization protocols. WebGL serves as a JavaScript API for rendering interactive two-dimensional and three-dimensional graphics within any compatible web browser without the use of plug-ins. The core technical flaw lies in the improper handling of resource allocation where specific data structures or buffers are accessed before they have been fully initialized with valid values. In C++ based environments like Chromium, this often manifests as a read-after-free scenario or an access to memory that has not yet been zeroed out or populated by legitimate application logic. When such uninitialized resources are exposed through the WebGL interface, the browser fails to validate whether the memory location contains safe, expected data prior to processing it for rendering operations. This lack of validation allows the internal state machine to operate on garbage values, leading to unpredictable behavior that can be exploited by malicious actors.
From an operational perspective, this vulnerability enables a remote attacker to achieve arbitrary code execution or sensitive information disclosure through a crafted HTML page hosted on a malicious website. The attack vector relies heavily on social engineering and web-based exploitation techniques where the victim is induced to visit a specially constructed webpage containing malicious JavaScript that interacts with WebGL contexts. By triggering specific rendering commands, the attacker can force the browser to read from memory regions outside the intended sandbox boundaries. This breach of the sandbox isolation model is particularly severe because Chrome employs a multi-process architecture designed to contain potential exploits within isolated renderer processes. However, when an uninitialized resource allows reading out-of-bounds memory, it effectively bypasses these containment mechanisms, granting the attacker access to data that should remain inaccessible, such as credentials stored in other tabs or sensitive application state from different domains.
The security severity of this flaw is classified as High due to its potential for remote code execution and information leakage without requiring user interaction beyond visiting a webpage. This aligns with Common Weakness Enumeration (CWE) standards, specifically CWE-457 which describes the use of an uninitialized variable, and potentially CWE-125 regarding out-of-bounds read vulnerabilities if the uninitialized data leads to accessing memory outside allocated buffers. Furthermore, in the context of the MITRE ATT&CK framework, this vulnerability facilitates techniques associated with Initial Access via Spearphishing Link or Drive-by Compromise, as well as Defense Evasion by bypassing sandbox restrictions. The exploitation chain typically involves crafting a WebGL shader program that triggers the uninitialized read condition during compilation or execution phases, allowing the attacker to leak memory contents back through JavaScript properties for further analysis and potential payload delivery.
Mitigation strategies primarily involve updating Google Chrome to version 157.0.8103.38 or later, where these initialization checks have been hardened by the Chromium security team. For organizations unable to patch immediately, network-level controls such as web application firewalls can be configured to detect and block known exploit patterns associated with WebGL memory corruption attempts, although this is less effective against zero-day variants. Additionally, enabling strict Content Security Policy headers helps restrict the execution of inline scripts that might attempt to leverage these vulnerabilities, reducing the attack surface available to remote attackers. It is also recommended for users to disable JavaScript on untrusted sites or utilize browser extensions that sandbox web content more aggressively until updates are applied across all endpoints within an enterprise environment.