CVE-2026-78961 in Chrome
Summary
by MITRE • 08/26/2026
Incorrect authorization in Core 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 access control mechanisms within the browser's core architecture, specifically affecting how permissions are validated during cross-origin interactions. This flaw is categorized under CWE-862, which denotes Missing Authorization, indicating that the software failed to properly enforce restrictions on what actions an authenticated user or process can perform. In the context of web browsers, this translates to a breakdown in the isolation boundaries that separate different origins, such as distinct websites or scripts running within iframes. The security severity is classified as Medium by Chromium standards because while it does not allow direct remote code execution from untrusted sites without additional steps, it significantly weakens the foundational trust model of the web platform when combined with other attack vectors.
The technical mechanism behind this vulnerability involves a lapse in how the renderer process handles authorization checks for certain privileged operations or API calls that should be restricted to specific origins. When an attacker compromises a renderer process through another vector, such as exploiting a separate memory corruption bug or leveraging malicious JavaScript execution within a sandboxed environment, they gain limited control over browser internals. However, this vulnerability allows that compromised renderer to escalate its privileges by bypassing the web origin policy. By crafting a specifically designed HTML page, an attacker can trick the user into interacting with it in a way that triggers the flawed authorization logic. This enables the malicious content to access resources or perform actions associated with other origins, effectively breaking the same-origin policy which is essential for preventing cross-site scripting and data theft attacks.
From an operational perspective, this vulnerability facilitates sophisticated phishing campaigns and session hijacking attempts. An attacker who has already achieved some level of code execution within a renderer process can use social engineering techniques to lure users into visiting a crafted webpage. Once the user interacts with this page, the browser's incorrect authorization logic allows the malicious script to read sensitive data from other tabs or domains that should remain isolated. This could lead to the exfiltration of cookies, local storage contents, or confidential form data belonging to banking sites, email services, or corporate portals where users are logged in. The impact is particularly severe because it undermines the browser's ability to maintain strict boundaries between different web contexts, potentially leading to unauthorized access to user accounts and sensitive personal information.
This behavior aligns with several techniques documented in the MITRE ATT&CK framework for enterprise security. Specifically, it relates to T1059, Command and Scripting Interpreter, as the attacker leverages JavaScript execution within the browser environment. Furthermore, it connects to T1534, Internal Spearphishing, where the attack relies on social engineering to manipulate users into triggering the vulnerability via a crafted HTML page. The bypass of web origin policy also maps to T1078, Valid Accounts, if the attacker uses stolen credentials or session tokens obtained through this breach of isolation. Understanding these mappings helps security teams identify similar patterns in threat intelligence and adjust detection rules accordingly.
To mitigate the risks associated with this vulnerability, organizations must ensure that all instances of Google Chrome are updated to version 152.0.7977.65 or later immediately upon availability. Since the attack vector involves social engineering and user interaction, security awareness training is crucial for educating users about the dangers of visiting untrusted websites or clicking on suspicious links, even if they appear legitimate. Additionally, implementing strict Content Security Policy headers can help restrict the execution of unauthorized scripts and limit the damage potential if a renderer process is compromised. Deploying browser isolation solutions or web application firewalls that inspect traffic for anomalous behavior related to origin bypass attempts can provide an additional layer of defense against exploitation of this flaw. Regular patch management cycles are essential to address such core security issues before they can be widely exploited in the wild.