CVE-2026-106425 in Chrome
Summary
by MITRE • 10/07/2026
Missing authorization in BrowserTag in Google Chrome prior to 155.0.8059.39 allowed a remote attacker who had compromised the renderer process and leveraged social engineering to bypass site isolation 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 missing authorization in BrowserTag within Google Chrome prior to version 155.0.8059.39 represents a significant breach of the browser's internal access control mechanisms, specifically targeting the isolation boundaries between different browsing contexts. This flaw resides in the communication channel or state management component known as BrowserTag, which is responsible for maintaining context-specific data and permissions during web page rendering. The core technical deficiency lies in the failure to enforce strict authorization checks when handling requests or updates related to these tags from compromised renderer processes. In a properly secured browser architecture, renderer processes operate with restricted privileges to prevent malicious code executed within a webpage from affecting other parts of the user's session or accessing sensitive data belonging to different sites. However, due to this missing authorization check, an attacker who has successfully achieved arbitrary code execution within a renderer process can interact with BrowserTag without proper validation of their authority to do so.
The operational impact of this vulnerability is primarily centered on the bypassing of site isolation policies, which are critical for preventing cross-site scripting and data leakage attacks. Site isolation ensures that content from different origins runs in separate processes, thereby limiting the ability of a malicious script running under one origin to access cookies, local storage, or DOM elements belonging to another origin. By leveraging social engineering techniques such as phishing pages or compromised legitimate websites, an attacker can trick users into visiting crafted HTML pages containing exploit code. Once executed within the renderer process, this code exploits the missing authorization in BrowserTag to manipulate browser state information across different origins. This effectively erodes the security boundary that site isolation is designed to maintain, potentially allowing the attacker to read sensitive data from other tabs or sites open in the same user session, such as authentication tokens, personal messages, or financial details stored by web applications.
From a classification perspective, this vulnerability aligns with CWE-269, which denotes Improper Privilege Assignment, specifically where an actor is granted privileges they should not possess based on their current context. Furthermore, the exploitation technique maps to MITRE ATT&CK techniques related to Defense Evasion and Credential Access, particularly those involving browser security feature bypasses or manipulation of process isolation mechanisms. The attack vector requires initial compromise of a renderer process, which typically necessitates successful social engineering or drive-by download tactics, followed by precise exploitation of this internal API flaw to escalate the impact from isolated script execution to cross-origin data access.
Mitigation for this vulnerability relies primarily on updating Google Chrome to version 155.0.8059.39 or later, where the authorization checks within BrowserTag have been reinforced to ensure that only authorized contexts can modify or query sensitive tag-related state information. For organizations managing large fleets of endpoints, enforcing automatic browser updates through endpoint management solutions is crucial to minimize exposure windows. Additionally, users should be educated on recognizing social engineering attempts and avoiding interaction with untrusted web content, as the initial entry point remains dependent on user action or compromised legitimate sites. Security monitoring tools that detect anomalous behavior in renderer processes attempting unauthorized IPC calls may also provide an additional layer of defense against exploitation of this specific flaw before patches are applied.