CVE-2026-121070 in Chrome
Summary
by MITRE • 11/03/2026
Use after free in WTF 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: Medium)
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Analysis
by VulDB Data Team • 11/03/2026
The vulnerability identified as a use-after-free flaw within the WebKit rendering engine, commonly referred to as WTF in Chromium-based browsers including Google Chrome prior to version 157.0.8103.38, represents a critical memory safety issue that undermines the browser's security model. This specific class of vulnerabilities occurs when a program continues to use a pointer after the memory it points to has been freed or reallocated. In the context of web browsers, this typically involves JavaScript objects or DOM elements where references are not properly invalidated upon deallocation. An attacker can exploit this by crafting an HTML page that triggers the premature release of a memory object while maintaining active references to that same memory region through script execution. When the browser subsequently attempts to access these dangling pointers, it reads from or writes to invalid memory locations, leading to undefined behavior that can be manipulated for malicious purposes.
The operational impact of this vulnerability is severe due to its potential for remote code execution within a sandboxed environment. Although modern browsers employ multiple layers of defense such as site isolation and hardware-enforced DEP protections, use-after-free bugs remain one of the most effective avenues for bypassing these safeguards if exploited correctly. By carefully controlling the memory layout through heap spraying techniques or other allocation strategies, an attacker can overwrite critical data structures within the browser process. This manipulation allows the execution of arbitrary machine code with the privileges of the compromised renderer process. While the sandbox restricts direct access to the host operating system, successful exploitation often leads to a sandbox escape, granting the attacker full control over the user's environment and enabling further lateral movement or persistent compromise.
From a classification perspective, this vulnerability aligns closely with CWE-416, which denotes Use After Free errors in software development. The attack vector is categorized under MITRE ATT&CK technique T1059, specifically Command and Scripting Interpreter, as the initial foothold involves executing code via JavaScript within the browser context. Furthermore, the exploitation path often relates to T1203, Exploitation for Client Execution, where a user interacts with a malicious webpage that triggers the vulnerability without requiring additional social engineering beyond luring them to visit the crafted site. The medium severity rating assigned by Chromium reflects the complexity of reliable exploitation and the presence of mitigating factors in recent browser versions, yet it remains high enough priority due to its direct link to arbitrary code execution capabilities.
Mitigation strategies primarily involve updating Google Chrome to version 157.0.8103.38 or later, where these memory management issues have been addressed through improved reference counting mechanisms and stricter validation of object lifecycles within the WebKit engine. Developers integrating Chromium-based technologies should ensure their dependencies are up-to-date with the latest security patches from upstream projects. Additionally, enabling advanced browser features such as Site Isolation can help contain potential exploits to individual tabs or processes, reducing the likelihood of a successful sandbox escape even if a vulnerability is present in an older version. Security teams should also monitor for indicators of compromise related to unusual memory allocation patterns or unexpected process behavior that may signal active exploitation attempts against unpatched systems.