CVE-2026-121123 in Chrome
Summary
by MITRE • 11/03/2026
Use after free in Canvas 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 • 11/04/2026
The vulnerability identified as a use-after-free error within the Canvas component of Google Chrome prior to version 157.0.8103.38 represents a critical memory management flaw that compromises the integrity of the browser's execution environment. This specific type of defect occurs when an application continues to reference a memory block after it has been freed, leading to undefined behavior that can be exploited by malicious actors. In this instance, the vulnerability resides in the Canvas API implementation, which is responsible for rendering graphics on web pages using JavaScript. The flaw allows a remote attacker to craft a specific HTML page containing malicious scripts designed to trigger the premature deallocation of memory objects while they are still being accessed or manipulated by the browser engine.
From a technical perspective, this vulnerability falls under the Common Weakness Enumeration category CWE-416, which defines use-after-free conditions as a result of improper handling of dynamic memory allocation and deallocation. When the Canvas component processes certain graphical operations triggered by the crafted HTML page, it fails to properly validate whether the underlying data structures are still valid before attempting to access them. This lapse in validation allows an attacker to control the contents of the freed memory region through heap spraying techniques or other exploitation methods. By carefully crafting the input and timing the execution of malicious code, the attacker can overwrite adjacent memory with controlled values, effectively gaining arbitrary read and write capabilities within the browser's process space.
The operational impact of this vulnerability is severe due to its potential for remote code execution inside the sandboxed environment that Chrome employs to isolate web content from the host operating system. Although modern browsers utilize multiple layers of security such as site isolation and hardware-based protections, a successful exploitation of a use-after-free bug can bypass these defenses if the attacker manages to achieve arbitrary memory writes followed by control flow hijacking. This could result in the execution of arbitrary code with the privileges of the browser process, potentially leading to full system compromise depending on the user's permissions and additional security configurations like sandboxing policies or endpoint detection tools.
This exploit scenario aligns closely with several techniques documented in the MITRE ATT&CK framework, particularly those related to initial access and privilege escalation within software applications. The use of a crafted HTML page indicates an attack vector consistent with drive-by downloads or malicious web pages designed to leverage browser vulnerabilities without requiring user interaction beyond visiting the site. Such attacks are often part of broader campaigns targeting specific industries or individuals through social engineering tactics that lead victims to visit compromised websites hosting these exploits.
Mitigation strategies primarily involve updating Google Chrome to version 157.0.8103.38 or later, where this memory management issue has been resolved by the Chromium development team. Organizations should ensure automatic updates are enabled for all endpoints running affected versions of the browser to minimize exposure windows. Additionally, implementing strict content security policies and restricting JavaScript execution on untrusted domains can reduce the attack surface available to potential exploiters. Security teams should also monitor network traffic for indicators of compromise associated with known exploitation kits targeting this specific vulnerability class and consider deploying advanced threat protection solutions capable of detecting anomalous browser behavior indicative of memory corruption attacks.