CVE-2026-121244 in Chrome
Summary
by MITRE • 11/03/2026
UI misrepresentation in FileAPI in Google Chrome prior to 157.0.8103.38 allowed a remote attacker leveraging social engineering to spoof UI elements via a crafted HTML page. (Chromium security severity: Medium)
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Analysis
by VulDB Data Team • 11/03/2026
The vulnerability identified as a user interface misrepresentation within the FileAPI of Google Chrome prior to version 157.0.8103.38 represents a significant trust boundary violation that exploits the browser's handling of file selection dialogs and associated UI elements. This flaw allows an attacker, through social engineering techniques such as hosting a malicious HTML page or embedding it within a phishing site, to manipulate how information is presented to the end user. Specifically, the vulnerability enables the spoofing of critical interface components, potentially making a malicious action appear legitimate or hiding the true nature of file operations from the user. By deceiving users about which files are being accessed or what permissions are being granted, this flaw undermines the fundamental security model that relies on informed consent and accurate visual feedback during interactive browser sessions.
From a technical perspective, this issue stems from improper validation or rendering logic within the Chromium engine's FileAPI implementation. When web pages request access to local file systems via standard APIs like window.showOpenFilePicker or similar legacy mechanisms, the browser is expected to display clear indicators of the origin and scope of the operation. In vulnerable versions, an attacker can craft HTML content that manipulates these UI elements to create a false sense of security or mislead the user regarding the actual data being transmitted. This type of attack falls squarely under CWE-201: Insertion of Sensitive Information into Sent Data, as it involves the injection of misleading context into the user interface rather than direct code execution. It also aligns with ATT&CK technique T1566.001: Phishing: Spearphishing Attachment or Link, where the primary vector is deceiving the victim through visual manipulation and social engineering rather than exploiting a traditional software bug like buffer overflow or injection flaws.
The operational impact of this vulnerability is primarily centered on data exfiltration and credential theft facilitated by user deception. If an attacker can successfully spoof UI elements to mimic legitimate system prompts or trusted application interfaces, they may trick users into selecting sensitive files such as configuration documents, personal photos, or financial records without realizing the consequences. Furthermore, if the misrepresentation extends to fake login dialogs or permission requests disguised as native browser notifications, it could lead to the compromise of user credentials or session tokens. The severity is rated as Medium because while it does not allow for direct remote code execution or kernel-level privilege escalation, it effectively bypasses human-based security controls by exploiting cognitive biases and trust in familiar interface patterns. This makes it particularly dangerous in enterprise environments where employees may be targeted with sophisticated phishing campaigns designed to harvest intellectual property or internal network credentials.
Mitigation strategies must focus on both immediate patching and long-term architectural improvements. The primary remediation is to update Google Chrome to version 157.0.8103.38 or later, which contains the necessary fixes for this UI misrepresentation flaw. Organizations should enforce automated browser update policies to ensure that all endpoints are protected against known vulnerabilities in a timely manner. Additionally, security awareness training plays a crucial role in mitigating social engineering attacks; users must be educated to verify the authenticity of file selection dialogs and permission requests by checking URL bars, certificate details, and contextual cues rather than relying solely on visual appearance. Implementing strict Content Security Policies (CSP) can also help restrict how scripts interact with UI elements, reducing the attack surface for such spoofing attempts. Regular security audits focusing on user interface integrity and adherence to OWASP guidelines for client-side protection will further harden defenses against these deceptive tactics.