CVE-2026-121126 in Chrome
Summary
by MITRE • 11/03/2026
Use after free in Core in Google Chrome prior to 157.0.8103.38 allowed a remote attacker to potentially execute arbitrary code outside the sandbox via a crafted HTML page. (Chromium security severity: Critical)
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Analysis
by VulDB Data Team • 11/04/2026
The vulnerability identified as a use-after-free condition within the core components of Google Chrome prior to version 157.0.8103.38 represents a critical memory management flaw that undermines the browser's foundational security model. This specific class of error occurs when a program continues to use a pointer after the memory it points to has been freed, often leading to undefined behavior that can be exploited by malicious actors. In the context of web browsers, such flaws are particularly dangerous because they reside in high-privilege processes or core rendering engines where access controls are less restrictive than in isolated renderer contexts. The presence of this vulnerability indicates a failure in the application's lifecycle management of memory objects, allowing an attacker to manipulate heap structures and potentially achieve arbitrary code execution with elevated privileges outside the confines of the browser sandbox.
From a technical perspective, use-after-free vulnerabilities typically arise when references to allocated memory are not properly invalidated after deallocation or when reference counting mechanisms fail to track object lifetimes accurately across asynchronous operations. An attacker can craft an HTML page that triggers specific JavaScript sequences or DOM manipulations designed to free a particular object while retaining active references to it elsewhere in the application state. By carefully controlling the timing and content of subsequent memory allocations, the adversary can force the system to reallocate the freed memory with maliciously crafted data structures. When the original code subsequently attempts to access this now-reallocated memory through the stale pointer, it effectively reads or writes arbitrary values into critical process memory spaces. This mechanism allows for precise control over program execution flow, enabling the injection and execution of shellcode that bypasses standard sandboxing protections designed to isolate web content from the underlying operating system.
The operational impact of this vulnerability is severe due to its potential for remote code execution via a crafted HTML page. Since modern browsers rely heavily on sandboxes to limit the damage caused by compromised websites, an exploit that escapes these boundaries poses a significant threat to user security and data integrity. Successful exploitation could allow an attacker to install malware, steal sensitive credentials stored in the browser, monitor keystrokes, or pivot further into internal networks if the victim is part of a corporate environment. The critical severity rating assigned by Chromium reflects the high likelihood of successful exploitation given the prevalence of such memory corruption bugs in complex web engines and the devastating consequences of breaking out of the sandbox isolation model. This aligns with common attack patterns observed in real-world campaigns where browser vulnerabilities are leveraged as initial access vectors for broader system compromise.
Industry standards classify this type of flaw under CWE-416, which defines use after free errors resulting from improper memory management practices that lead to unpredictable behavior and potential security breaches. Furthermore, the exploitation technique maps directly to MITRE ATT&CK techniques related to execution within a sandbox escape scenario, specifically leveraging memory corruption to bypass isolation mechanisms. 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 audits and enhanced heap sanitization features such as ASAN (Address Sanitizer) integration during development cycles. Organizations should also enforce strict browser update policies across all endpoints to ensure that known vulnerabilities in core components are patched promptly. Additionally, deploying endpoint detection and response solutions capable of identifying anomalous memory access patterns can provide an additional layer of defense against exploitation attempts targeting unpatched or legacy systems.