CVE-2026-79228
Summary
by MITRE • 08/26/2026
Incorrect authorization in SiteIsolation in Google Chrome prior to 152.0.7977.65 allowed a remote attacker who had compromised the renderer process to bypass site isolation into a privileged page 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 incorrect authorization flaw within Google Chrome's SiteIsolation mechanism prior to version 152.0.7977.65 represents a significant breach in the browser's process isolation architecture. SiteIsolation is a critical security feature designed to prevent cross-site scripting attacks and data theft by ensuring that each site runs in its own unique renderer process, thereby isolating it from other sites. This vulnerability arises when the authorization checks governing access between these isolated processes are insufficiently rigorous or incorrectly implemented. Specifically, the flaw allows a remote attacker who has already achieved code execution within a compromised renderer process to bypass the intended boundaries and interact with privileged pages belonging to different origins. The severity of this issue is classified as Medium by Chromium security standards, reflecting its potential for exploitation while acknowledging that it requires an initial compromise of the renderer environment rather than being directly exploitable from untrusted web content without prior foothold.
From a technical perspective, the core flaw lies in the failure of the authorization logic to properly validate permissions when transitioning context or accessing resources across process boundaries. In a correctly functioning SiteIsolation model, even if an attacker compromises one renderer process through a separate vulnerability such as a use-after-free or type confusion bug, they should be restricted from reading sensitive data or executing scripts within processes handling high-privilege content like banking sessions or email accounts. However, due to the incorrect authorization check, the compromised renderer can craft specific HTML structures that trick the browser into granting access to these privileged contexts. This bypass effectively neutralizes one of Chrome's most important defenses against cross-site attacks, allowing for potential data exfiltration or session hijacking if the user is logged into sensitive services during the attack window.
The operational impact of this vulnerability is substantial for users who rely on Google Chrome for secure web browsing, particularly those engaged in online banking, e-commerce, or accessing corporate intranets. An attacker leveraging this flaw could potentially access cookies, local storage data, or DOM content from other tabs that are protected by SiteIsolation under normal circumstances. This capability undermines the principle of least privilege within the browser environment and increases the attack surface for subsequent exploits such as credential theft or unauthorized transactions. While the vulnerability requires an initial compromise of a renderer process, which typically involves exploiting another distinct flaw, its existence lowers the barrier for attackers to escalate their privileges from a low-level script execution to accessing high-value data across site boundaries.
To mitigate this risk, users are strongly advised to update Google Chrome immediately to version 152.0.7977.65 or later, where these authorization checks have been corrected and the integrity of SiteIsolation has been restored. For organizations deploying Chrome at scale, it is essential to ensure that automatic updates are enabled or to deploy patching policies through enterprise management tools to minimize exposure windows. Additionally, security teams should monitor for indicators of compromise related to renderer process anomalies and consider implementing additional layers of defense such as strict Content Security Policies where applicable. Although no known exploits were reported at the time of disclosure, proactive remediation is critical given the high value placed on browser isolation mechanisms in modern web security architectures. This incident underscores the importance of rigorous code review for inter-process communication logic within complex software systems like browsers to prevent subtle authorization bypasses that can have severe consequences for user data privacy and integrity.