CVE-2026-106266 in Chrome
Summary
by MITRE • 10/06/2026
Confused deputy in Contextual Tasks in Google Chrome prior to 155.0.8059.39 allowed a remote attacker who had compromised the renderer process to bypass web origin policy into a privileged page via a crafted HTML page. (Chromium security severity: Medium)
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Analysis
by VulDB Data Team • 10/07/2026
The vulnerability identified as a confused deputy issue within Google Chrome prior to version 155.0.8059.39 represents a significant breach in the browser's isolation model, specifically targeting the boundary between untrusted renderer processes and privileged pages such as internal chrome:// URLs or extension contexts. This flaw stems from an improper check of execution context during the handling of contextual tasks, which are asynchronous operations that may be scheduled by web content but executed within different security scopes. When a remote attacker crafts a malicious HTML page designed to exploit this race condition or logic error, they can trick the browser into treating untrusted renderer-originated actions as if they originated from a trusted context. This misattribution of authority allows the attacker to bypass strict web origin policies that are fundamentally designed to prevent cross-site scripting and unauthorized data access between different origins.
From a technical perspective, this vulnerability falls under the category of privilege escalation within the application layer, specifically aligning with CWE-269: Improper Privilege Management. The core issue lies in the browser's internal mechanism for validating whether an action initiated by web content is permitted to interact with higher-privilege interfaces. In a secure implementation, any interaction between renderer processes and privileged components must undergo rigorous origin verification and permission checks. However, due to this flaw, certain contextual tasks bypass these critical validations, effectively granting the compromised renderer process capabilities it should not possess. This allows an attacker who has already achieved code execution within a sandboxed tab to escalate their privileges and access sensitive data or execute commands in contexts that are normally isolated from web content, such as browser settings, history, or extension management interfaces.
The operational impact of this vulnerability is severe for users browsing untrusted websites, particularly those on public Wi-Fi networks or sites known for hosting malicious scripts. An attacker leveraging this flaw can exfiltrate sensitive information stored in privileged pages, manipulate browser state to facilitate further attacks such as phishing by altering the address bar display, or install persistent malware components if extension APIs are accessible from the elevated context. This undermines the fundamental trust model of modern web browsers, where users rely on the assumption that a compromised webpage cannot affect other parts of the browsing session or system configuration. The severity is rated as medium because while it requires initial compromise of the renderer process, which often involves exploiting another vulnerability or using social engineering to execute malicious code, once achieved, it provides a powerful foothold for deeper system infiltration and data theft.
To mitigate this risk, users must ensure that Google Chrome is updated to version 155.0.8059.39 or later immediately upon availability. This update contains the necessary patches to enforce stricter origin checks on contextual tasks, ensuring that actions originating from untrusted web content cannot be misattributed to privileged contexts. Additionally, security administrators should monitor for indicators of compromise related to renderer process anomalies and consider implementing strict Content Security Policies (CSP) across organizational domains to limit the potential impact of any successful exploitation attempts. From a defensive posture perspective, this incident highlights the importance of continuous patch management and the need for robust sandboxing mechanisms that are regularly audited against evolving attack vectors such as confused deputy scenarios. The ATT&CK framework categorizes similar behaviors under T1059: Command and Scripting Interpreter or potentially T1210: Exploitation of Remote Services, depending on how the initial renderer compromise was achieved, emphasizing the need for layered defense strategies that include endpoint detection and response tools capable of identifying unusual privilege escalation patterns within browser processes.