CVE-2026-78943 in Chrome
Summary
by MITRE • 08/26/2026
Improper input validation in Editing in Google Chrome prior to 152.0.7977.65 allowed a remote attacker who had compromised the renderer process and leveraged social engineering to bypass web origin policy via a crafted HTML page. (Chromium security severity: Medium)
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Analysis
by VulDB Data Team • 08/26/2026
The vulnerability identified in Google Chrome prior to version 152.0.7977.65 represents a critical failure in input validation mechanisms within the browser's editing subsystem. This flaw, classified under CWE-20 as Improper Input Validation, allows for the manipulation of internal state by accepting malformed or unexpected data structures that were not adequately sanitized before processing. The specific context involves the handling of HTML content during user interactions with editable regions on web pages. When a renderer process receives input intended to modify document structure or style, it fails to strictly enforce boundaries between trusted and untrusted data sources. This lack of rigorous validation creates an opening for attackers who have already achieved code execution within the sandboxed renderer environment to inject malicious payloads that exploit these weak checks.
The operational impact of this vulnerability centers on the potential bypassing of web origin policies, which are fundamental security constructs designed to isolate content from different origins to prevent unauthorized access to sensitive data. By leveraging social engineering techniques, an attacker can craft a deceptive HTML page that tricks a user into interacting with specific elements or triggering certain events within the browser interface. Once the victim engages with this crafted content, the renderer process executes code that exploits the input validation flaw. This allows the malicious script to escape its intended sandbox constraints and interact with resources belonging to different origins than where it originated. Such a breach undermines the isolation model of modern web browsers, potentially leading to unauthorized data exfiltration or session hijacking if combined with other vulnerabilities like cross-site scripting flaws in target sites.
From an offensive security perspective, this vulnerability aligns with ATT&CK technique T1059, specifically Command and Scripting Interpreter sub-techniques that involve browser-based execution. The attacker relies on the renderer process being compromised first, which often occurs through drive-by downloads or malicious advertisements containing exploit code targeting other vulnerabilities in rendering engines like Blink. Once inside the renderer, the exploitation of this editing input validation flaw serves as a privilege escalation vector within the browser's architecture. It enables the transition from restricted sandboxed execution to broader access over web-origin boundaries. This progression is particularly dangerous because it allows attackers to target high-value assets such as banking portals or corporate intranets that rely heavily on strict origin policies for security.
Mitigation strategies primarily involve updating Google Chrome to version 152.0.7977.65 or later, where the input validation logic in the editing component has been hardened. Developers and system administrators should ensure automatic updates are enabled to receive these patches promptly as they become available. For organizations deploying browsers at scale, implementing application control policies can restrict the execution of untrusted scripts within renderer processes, thereby reducing the attack surface even if such vulnerabilities exist. Additionally, user education regarding social engineering tactics remains crucial since this exploit requires initial user interaction with a crafted page. Security monitoring tools should be configured to detect anomalous behavior patterns indicative of origin policy bypass attempts, although detection at the endpoint level may require advanced behavioral analytics due to the sophisticated nature of browser-based exploits.