CVE-2026-121140 in Chrome
Summary
by MITRE • 11/03/2026
Out of bounds read in Internals in Google Chrome prior to 157.0.8103.38 allowed a remote attacker who had compromised the renderer process to potentially execute arbitrary code outside 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 an out-of-bounds read within Google Chrome's Internals component represents a significant memory safety flaw that undermines the browser's core isolation mechanisms. This specific defect occurs when the application attempts to access data structures beyond their allocated boundaries, leading to the reading of unintended memory contents. While traditional out-of-bounds reads are often associated with information disclosure or denial of service scenarios, in the context of modern web browsers and complex JavaScript engines like V8, such flaws can frequently be chained with other techniques to achieve arbitrary code execution. The severity is classified as high by Chromium security standards due to the potential for privilege escalation from a sandboxed environment to the host system level under specific conditions.
The operational impact centers on the compromise of the renderer process isolation model. Modern browsers utilize multi-process architectures where each tab or site runs in a restricted sandbox, preventing malicious code from directly accessing sensitive user data or system resources. However, if an attacker can exploit this out-of-bounds read to leak critical memory addresses or object metadata, they may be able to bypass these sandboxes through techniques such as heap spraying and type confusion attacks. By crafting a specific HTML page that triggers the vulnerability during its parsing or execution phase, an adversary can manipulate the browser's internal state in ways that allow for arbitrary code execution outside the protective boundaries of the renderer process. This effectively neutralizes one of the primary defenses against web-based malware and drive-by download attacks.
From a threat modeling perspective, this flaw aligns with CWE-125, which describes out-of-bounds read vulnerabilities where software reads data past the end or before the beginning of the intended buffer. Furthermore, it relates to ATT&CK technique T1059, Command and Scripting Interpreter, as the exploitation typically involves executing scripts within the browser environment that subsequently escalate privileges. The attack vector is remote, requiring only a user interaction such as visiting a maliciously crafted webpage or having one loaded automatically via drive-by download mechanisms. This makes it particularly dangerous in scenarios involving phishing campaigns or compromised advertising networks where users may inadvertently trigger the exploit without explicit intent to run harmful code.
Mitigation strategies primarily involve applying the latest security patches provided by Google Chrome, which address the memory management errors within the Internals component and related rendering engines. Organizations should ensure that endpoint detection and response systems are configured to monitor for unusual process creation events originating from browser processes, as this can indicate successful exploitation of sandbox escape vulnerabilities. Additionally, implementing strict content security policies and disabling unnecessary JavaScript features in high-risk environments can reduce the attack surface available to adversaries attempting to leverage such memory corruption flaws. Regular updates to all components within the Chromium ecosystem are essential to maintain the integrity of the isolation model against evolving exploit techniques.