CVE-2026-87465 in Chrome
Summary
by MITRE • 09/09/2026
Incorrect authorization in Downloads in Google Chrome prior to 153.0.8010.36 allowed a remote attacker who had compromised the renderer process to spoof UI elements 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 issue within the Downloads component of Google Chrome prior to version 153.0.8010.36 represents a significant breach in process isolation and user interface integrity. This flaw specifically affects the mechanism by which download operations are managed, allowing for unauthorized manipulation of visual elements presented to the end-user. The core technical deficiency lies in the insufficient validation of permissions when rendering or updating UI components associated with file downloads. In modern browser architectures like Chromium, different tasks such as network requests, script execution, and user interface updates are segregated into distinct processes to limit the blast radius of a compromise. However, this vulnerability indicates that the boundary between the renderer process, which handles web content, and the higher-privilege UI or download manager components was not strictly enforced in certain contexts involving crafted HTML pages.
The operational impact of this flaw centers on the ability of an attacker who has already achieved code execution within a compromised renderer process to spoof user interface elements. This is typically achieved through cross-site scripting techniques or by exploiting race conditions and logic errors in how download notifications are generated and displayed. By crafting specific HTML content, an adversary can inject deceptive prompts that mimic legitimate browser behaviors, such as fake save dialogs, misleading progress bars, or counterfeit security warnings. These spoofed UI elements serve to deceive the user into believing they are interacting with a trusted system component rather than malicious code injected by the attacker. This deception is particularly dangerous because it undermines the trust model of the browser, leading users to make incorrect decisions regarding file saves and data handling based on false visual cues provided by the compromised page.
From a threat modeling perspective, this vulnerability aligns closely with CWE-269, which denotes Improper Privilege Assignment, as well as CWE-749, Exposed Dangerous Method or Function, depending on the specific implementation details of how the UI elements were exposed to lower-privileged contexts. Furthermore, in terms of the MITRE ATT&CK framework for enterprise security, this behavior is indicative of techniques related to Defense Evasion and User Interaction. Specifically, it relates to Obfuscated Files or Information when used to hide malicious intent behind legitimate-looking interfaces, and potentially to Social Engineering via Impersonation if the spoofed elements are designed to mimic system alerts. The severity is classified as Medium within the Chromium security model because while it does not allow direct arbitrary code execution from a sandboxed tab without prior compromise, it significantly enhances the effectiveness of existing renderer exploits by adding a layer of social engineering and user deception that can lead to further compromises such as malware installation or credential theft.
Mitigation for this vulnerability requires immediate updates to Google Chrome versions 153.0.8010.36 and later, where these authorization checks have been strengthened. For organizations unable to patch immediately due to operational constraints, implementing strict Content Security Policy headers can help mitigate the risk by restricting the sources from which scripts and resources are loaded, thereby reducing the attack surface for renderer-based exploits. Additionally, user education remains critical; administrators should advise users to verify download origins through independent channels rather than relying solely on browser UI prompts when dealing with unexpected or unsolicited downloads. Regular auditing of browser configurations and ensuring that automatic updates are enabled can also help maintain a robust defense posture against such privilege escalation and spoofing attacks within the web browsing environment.