CVE-2026-121035 in Chrome
Summary
by MITRE • 11/03/2026
Use after free in Prerender in Google Chrome prior to 157.0.8103.38 allowed a remote attacker to execute arbitrary code outside the sandbox via a crafted HTML page. (Chromium security severity: Critical)
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Analysis
by VulDB Data Team • 11/03/2026
The vulnerability identified as a use-after-free flaw within the Prerender component of Google Chrome prior to version 157.0.8103.38 represents a critical memory corruption issue that undermines the browser's sandboxing mechanisms. This specific class of vulnerabilities occurs when a program continues to use a pointer after it has been freed, leading to undefined behavior that can be exploited by malicious actors. In this context, the Prerender feature is designed to load web pages in advance based on user navigation predictions, optimizing performance and reducing latency. However, improper memory management within this component allowed for an attacker-controlled state where allocated memory was deallocated but still referenced by active processes or data structures associated with the prerendering task.
The technical flaw stems from a failure to properly invalidate pointers or update references after memory release operations during the lifecycle of a prerendered page. When a remote attacker hosts a crafted HTML page, they can trigger specific sequences of events that cause the browser engine to free certain internal objects while retaining active handles or callbacks pointing to those same memory locations. By carefully crafting the payload and timing the interaction with these dangling pointers, an attacker can manipulate what data is written into the freed memory region. This manipulation allows for arbitrary code execution because the attacker can overwrite function pointers, virtual table entries, or other critical control flow structures within the browser process space.
The operational impact of this vulnerability is severe due to its potential to bypass Chrome's sandboxing architecture. The sandbox restricts what a web page can do with system resources and file access, but it relies on the integrity of the underlying engine processes. A successful exploitation of this use-after-free condition enables an attacker to execute arbitrary code outside these restricted boundaries. This means that once the exploit is triggered through a simple visit to a malicious website or via drive-by download techniques embedded in such a page, the attacker gains full control over the compromised browser process and potentially escalates privileges to interact with the underlying operating system. The Chromium security severity rating of Critical reflects this high risk profile, as it directly compromises user confidentiality, integrity, and availability by allowing remote code execution without any additional interaction beyond visiting the malicious site.
This vulnerability aligns closely with Common Weakness Enumeration (CWE) category CWE-416, which describes Use After Free errors where a pointer is used after its memory has been freed. Furthermore, in terms of offensive security frameworks such as MITRE ATT&CK, this exploit technique falls under the Tactic Execution and Persistence categories, specifically leveraging techniques like Arbitrary Code Injection or Memory Corruption to achieve initial access and potentially lateral movement within an enterprise environment if browser compromise leads to further system infiltration. The ability to execute code outside the sandbox effectively neutralizes one of the primary defense layers in modern web browsers, making immediate remediation essential for maintaining security posture.
Mitigation strategies primarily involve updating Google Chrome to version 157.0.8103.38 or later, where these memory management issues have been addressed through rigorous code reviews and automated fuzzing tests designed to detect dangling pointer scenarios. For organizations unable to update immediately due to compatibility constraints, implementing strict content security policies can help mitigate some risks by restricting the types of scripts that can execute within prerendered contexts. Additionally, deploying browser isolation solutions or web application firewalls that inspect traffic for known exploit patterns related to memory corruption in Chromium-based browsers provides an additional layer of defense. Regular patch management and monitoring for emerging exploits targeting this specific component are critical steps in reducing exposure to such high-severity vulnerabilities.