CVE-2026-87580 in Chrome
Summary
by MITRE • 09/09/2026
Incorrect authorization in WebAppInstalls in Google Chrome prior to 153.0.8010.36 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 • 09/09/2026
The vulnerability identified as an incorrect authorization flaw within the WebAppInstalls component of Google Chrome prior to version 153.0.8010.36 represents a significant breach in the browser's access control mechanisms. This issue stems from improper checks regarding user permissions when handling web application installation requests, allowing for unauthorized actions that undermine the security model designed to protect users and their data. The root cause lies in how the renderer process interacts with higher-privilege components during the execution of install-related APIs, where the system fails to adequately verify whether the initiating context has the requisite authority to perform specific operations related to web app installation or modification.
From a technical perspective, this flaw exploits the trust relationship between different browser processes. In modern browsers like Chrome, site isolation is a critical security feature that restricts how content from one origin can interact with another, thereby preventing cross-site scripting and data leakage attacks. However, by leveraging social engineering techniques to trick a user into visiting a crafted HTML page, an attacker could manipulate the renderer process to issue requests that bypass these isolation boundaries. The renderer, while typically sandboxed, possesses certain capabilities when interacting with native features like web app installations. If authorization checks are insufficient, this capability can be abused to execute actions outside the intended scope of the current origin, effectively breaking down the barriers meant to contain malicious code within its specific context.
The operational impact of this vulnerability is substantial because it allows a remote attacker who has already compromised or influenced the renderer process through social engineering to bypass site isolation. This means that an attacker could potentially access sensitive data from other tabs or sites running in different origins, leading to potential information disclosure or further privilege escalation within the browser environment. The severity rating of Medium reflects the complexity involved; while it requires user interaction via social engineering and a pre-existing compromise of the renderer process, its ability to circumvent site isolation makes it particularly dangerous for users who rely on Chrome's security features to maintain privacy across multiple web sessions.
This vulnerability aligns with CWE-269, which describes Improper Privilege Assignment, as the system failed to enforce appropriate access controls during critical operations. Furthermore, from an offensive security standpoint, this behavior is consistent with techniques found in the MITRE ATT&CK framework under T1053, specifically related to scheduled tasks or background processes that can be manipulated for persistence or lateral movement within a compromised environment. The exploitation vector relies heavily on social engineering (T1566), highlighting the importance of user awareness alongside technical controls.
To mitigate this risk, users are strongly advised to update Google Chrome immediately to version 153.0.8010.36 or later, where these authorization checks have been corrected and reinforced. Additionally, maintaining up-to-date security software and employing strict content security policies can help reduce the attack surface available to such exploits. For developers integrating web app installation features, it is crucial to ensure that all permission requests are validated against current user privileges before execution, adhering strictly to least-privilege principles to prevent unauthorized access even if other parts of the system are compromised.