CVE-2026-121117 in Chrome
Summary
by MITRE • 11/03/2026
Use after free in Paint 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 flaw within the Paint component of Google Chrome prior to version 157.0.8103.38 represents a critical memory management error that compromises the integrity of the browser's sandboxing mechanisms. This specific class of vulnerabilities arises when an application continues to reference a pointer after the memory it points to has been freed, leading to undefined behavior that can be exploited by malicious actors. In this instance, the flaw resides in how Chrome handles graphical rendering operations associated with paint events, where objects are deallocated but subsequent code attempts to access or manipulate them based on stale pointers. This discrepancy creates a window of opportunity for an attacker to inject arbitrary data into freed memory regions, effectively controlling the state of the application during execution.
From a technical perspective, use-after-free vulnerabilities are particularly dangerous because they allow attackers to achieve arbitrary read and write primitives within the process space of the browser. By carefully crafting HTML content that triggers specific paint operations followed by deallocation events, an attacker can manipulate heap metadata or overwrite adjacent objects with controlled values. This manipulation enables the execution of arbitrary code inside the sandboxed environment, which is designed to isolate web content from the underlying operating system and user data. The severity rating of High in Chromium reflects the potential for this flaw to be leveraged in sophisticated attacks that bypass standard security controls, potentially leading to full compromise of the victim's machine if additional exploitation steps are successfully executed.
The operational impact of such a vulnerability is severe, as it undermines one of the primary defenses against web-based threats: process isolation. When an attacker can execute arbitrary code within the sandbox, they may escalate privileges by exploiting subsequent vulnerabilities or leveraging browser features to escape the restricted environment entirely. This could result in unauthorized access to sensitive files, installation of malware, keystroke logging, and other forms of data exfiltration. The risk is amplified because these exploits often require no user interaction beyond visiting a maliciously crafted webpage, making them suitable for drive-by download attacks where victims are compromised simply by loading the page without clicking any links or downloading additional files.
Industry standards classify this type of vulnerability under CWE-416, which defines use after free as accessing memory that has already been freed, often leading to crashes or arbitrary code execution. In terms of attack tactics, this aligns with MITRE ATT&CK techniques related to initial access and privilege escalation, specifically those involving exploitation of software vulnerabilities for remote code execution. Mitigating such risks requires a multi-layered approach including rigorous memory safety practices in browser development, such as using smart pointers or garbage collection mechanisms that prevent dangling references. Additionally, deploying advanced runtime protection technologies like heap spraying mitigations, control flow integrity checks, and sandboxing enhancements can significantly reduce the exploitability of these flaws. Users should ensure their browsers are updated to version 157.0.8103.38 or later immediately to patch this vulnerability and maintain a secure browsing environment against emerging threats.