CVE-2026-118342 in Chrome
Summary
by MITRE • 10/28/2026
Out of bounds write in Editing in Google Chrome prior to 156.0.8078.73 allowed a remote attacker 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 • 10/28/2026
The vulnerability identified as an out-of-bounds write within the editing component of Google Chrome prior to version 156.0.8078.73 represents a critical memory corruption flaw that undermines the browser's core security architecture. This specific type of error occurs when a program writes data beyond the boundaries of allocated memory buffers, which can lead to unpredictable behavior including crashes or arbitrary code execution. In this instance, the defect resides in the editing subsystem responsible for handling rich text and content manipulation within web pages. When a user visits a maliciously crafted HTML page designed to exploit this flaw, the browser processes input data that triggers an invalid write operation outside the intended memory region. This scenario is particularly dangerous because it allows a remote attacker who controls the webpage to influence the internal state of the browser process in ways not anticipated by the developers.
The operational impact of this vulnerability extends beyond simple application instability or denial of service, although those are possible outcomes if the corruption causes a crash. The primary concern lies in the potential for arbitrary code execution outside the sandbox environment that Chrome employs to isolate web content from the host operating system. Modern browsers utilize sandboxes to restrict what web pages can do with local resources such as files, network connections, and hardware devices. By exploiting an out-of-bounds write within a privileged or semi-privileged component like the editing engine, an attacker may be able to overwrite critical data structures that control execution flow or memory protection mechanisms. This could allow the malicious code to escape the sandbox boundary, thereby gaining higher privileges on the victim's machine and potentially leading full system compromise.
From a classification perspective, this vulnerability aligns with CWE-787: Out-of-bounds Write, which is categorized as a high-severity issue due to its potential for remote code execution. The attack vector corresponds to ATT&CK technique T1203: Exploitation for Client Execution, where the adversary relies on user interaction or automated browsing of malicious content to trigger the exploit chain. The Chromium security team has rated this flaw with High severity, reflecting the significant risk it poses to users who browse untrusted websites. Such vulnerabilities often require complex exploitation techniques involving heap spraying or specific memory layout conditions to reliably achieve code execution, but even probabilistic success rates make them serious threats in automated drive-by download scenarios.
Mitigation strategies for this vulnerability primarily involve updating Google Chrome to version 156.0.8078.73 or later, where the underlying memory management logic has been corrected to validate buffer boundaries before performing write operations. Organizations should enforce automatic update policies across all endpoints running Chromium-based browsers to ensure timely patching of such critical flaws. Additionally, users can reduce their exposure by employing browser hardening techniques such as disabling JavaScript on untrusted sites or using extensions that restrict content execution permissions. Security monitoring tools may also detect anomalous memory access patterns associated with exploitation attempts, although detection at the endpoint level remains challenging without specialized behavioral analysis capabilities. Regular patch management and adherence to vendor security advisories remain the most effective defense against these types of in-the-wild exploits targeting widely deployed software components.