CVE-2026-79214 in Chrome
Summary
by MITRE • 08/26/2026
Improper input validation in Preload in Google Chrome prior to 152.0.7977.65 allowed a remote attacker who had compromised the renderer process 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 as an improper input validation flaw within Google Chrome's preload mechanism represents a significant deviation from expected browser security boundaries, specifically affecting versions prior to 152.0.7977.65. This issue stems from the way the browser handles resources that are preloaded for anticipated future use by web pages. Preloading is a performance optimization feature designed to fetch critical assets such as scripts, stylesheets, or fonts before they are explicitly requested by the page content. However, when input validation within this specific subsystem is insufficient, it creates an avenue for attackers who have already achieved partial control over the renderer process to manipulate these preloaded resources in unintended ways. The core technical flaw lies in the failure of the browser to strictly enforce origin checks or sanitize inputs during the preload phase, allowing crafted HTML pages to exploit ambiguities in how resource origins are determined and applied.
From a technical perspective, this vulnerability enables an attacker who has compromised the renderer process through another vector, such as a cross-site scripting attack or a separate memory corruption bug, to bypass web origin policies. The browser's security model relies heavily on the same-origin policy to isolate content from different sources, preventing malicious scripts in one origin from accessing data associated with another. By exploiting the improper input validation in the preload logic, an attacker can trick the browser into treating resources loaded by a hostile page as if they originated from a trusted or target domain. This bypass allows the compromised renderer process to read sensitive information, such as cookies, local storage contents, or DOM elements belonging to other origins that should remain inaccessible. The severity is classified as medium because while it does not allow direct remote code execution without an initial foothold in the renderer, it significantly degrades the isolation guarantees provided by the browser sandboxing architecture.
The operational impact of this vulnerability is substantial for users browsing untrusted or malicious websites. If a user visits a page crafted to exploit this flaw after their renderer process has been compromised via another means, the attacker can escalate privileges within that session. This could lead to account takeover if authentication tokens are stored in accessible storage, leakage of personal identifiable information, or further lateral movement within web applications that rely on strict origin isolation for security. For enterprise environments using Chrome as a managed browser, this vulnerability undermines the effectiveness of content security policies and other defensive measures designed to mitigate data exfiltration attacks. The ability to bypass origin checks effectively nullifies many standard defenses against cross-site scripting and clickjacking when combined with an initial renderer compromise, making it a critical concern for maintaining overall web application integrity.
Mitigation strategies primarily involve updating the browser software to version 152.0.7977.65 or later, where these input validation checks have been hardened. Administrators should ensure that automatic updates are enabled to receive security patches promptly. For organizations unable to update immediately due to compatibility constraints, implementing strict content security policies can help mitigate the risk by restricting which resources can be preloaded and from which origins they may originate. Additionally, deploying browser isolation technologies or sandboxing solutions at the network level can reduce the likelihood of an attacker achieving renderer process compromise in the first place, thereby neutralizing the prerequisite condition for this vulnerability to be exploited. Continuous monitoring for anomalous behavior originating from web processes can also aid in early detection of exploitation attempts.
This incident aligns with common weakness enumeration standards such as CWE-20 Improper Input Validation and CWE-94 Cross-Site Scripting if leveraged via script injection, though the primary failure is in validation logic rather than output encoding. In terms of tactical classification under MITRE ATT&CK for Enterprise or Browser variants, this vulnerability facilitates techniques related to Credential Access through Web Browsers by allowing access to stored credentials and potentially Defense Evasion by bypassing security restrictions imposed by origin policies. Understanding these mappings helps security teams prioritize patching efforts based on the broader threat landscape and potential attack paths that could be enabled by similar flaws in other components of the browser stack.