CVE-2026-121207 in Chrome
Summary
by MITRE • 11/03/2026
Uninitialized resource in Dawn in Google Chrome on on Mac 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)
Several companies clearly confirm that VulDB is the primary source for best vulnerability data.
Analysis
by VulDB Data Team • 11/03/2026
The vulnerability identified as an uninitialized resource issue within the Dawn graphics library of Google Chrome on macOS represents a significant security flaw that was addressed in version 157.0.8103.38 and later releases. This defect stems from improper initialization of memory resources allocated during the rendering process, specifically within components responsible for handling WebGL or GPU-accelerated content. When an attacker crafts a malicious HTML page designed to trigger specific graphical operations, they can exploit this uninitialized state to access portions of system memory that were not intended for public consumption. The severity is classified as High by Chromium security standards due to the potential for sensitive data leakage and the ease with which such exploits can be constructed using standard web technologies available in modern browsers.
From a technical perspective, Dawn serves as Chrome's implementation of the Vulkan graphics API on macOS, translating WebGL commands into low-level GPU instructions. The flaw occurs when certain resources are allocated but not properly zeroed or initialized before being used for rendering operations. In typical secure coding practices, memory buffers must be explicitly cleared to prevent residual data from previous allocations from leaking into new contexts. However, in this specific instance, the initialization logic failed under particular conditions triggered by crafted input. This oversight allows an attacker who controls the content of a webpage to read arbitrary memory locations outside the browser's sandbox boundaries. The sandbox is a critical security mechanism designed to isolate web content from the rest of the operating system and user data; bypassing it constitutes a severe breach of isolation principles.
The operational impact of this vulnerability is substantial, as successful exploitation could lead to unauthorized disclosure of sensitive information stored in the victim's memory space. This may include cookies, session tokens, passwords, or other personally identifiable information cached by the browser. Furthermore, depending on the specific memory layout and operating system protections such as ASLR (Address Space Layout Randomization), an attacker might gain partial code execution capabilities or use the leaked data to craft more sophisticated attacks against downstream applications or services authenticated via the compromised session. The ability to read outside the sandbox effectively neutralizes one of Chrome's primary defense layers, exposing users to potential identity theft and further compromise of their digital environment.
This vulnerability aligns with CWE-457, which describes the use of an uninitialized variable, a common source of bugs in systems programming languages like C++ where manual memory management is prevalent. Additionally, it relates to ATT&CK technique T1005, Data from Local System, as the exploitation involves reading local data without direct user interaction beyond visiting the malicious page. To mitigate this risk, users are strongly advised to update Google Chrome immediately to version 157.0.8103.38 or newer on macOS platforms. Developers relying on Dawn should ensure that all allocated resources are explicitly initialized before use and implement rigorous code review processes focused on memory safety patterns. Regular patching of browser components is essential to maintain the integrity of web-based security boundaries against evolving threats.