CVE-2025-6428 in Firefox
Summary
by MITRE • 06/24/2025
When a URL was provided in a link querystring parameter, Firefox for Android would follow that URL instead of the correct URL, potentially leading to phishing attacks. *This bug only affects Firefox for Android. Other versions of Firefox are unaffected.* This vulnerability affects Firefox < 140.
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Analysis
by VulDB Data Team • 08/17/2025
This vulnerability represents a critical client-side redirection flaw that specifically targets Firefox for Android users, creating a significant security risk through potential phishing vector exploitation. The issue manifests when the browser encounters a URL provided within a link querystring parameter, causing it to navigate to an unintended destination rather than the legitimate target. This behavior fundamentally undermines the browser's expected navigation flow and creates opportunities for malicious actors to craft deceptive web experiences that could trick users into visiting fraudulent sites. The vulnerability's impact is particularly concerning given the mobile browsing environment where users may be less vigilant about URL verification due to smaller screen sizes and different interaction patterns compared to desktop browsing.
The technical nature of this flaw stems from improper handling of URL parsing and redirection logic within Firefox's Android implementation. When processing web links containing querystring parameters, the browser's URL resolution mechanism fails to properly validate or sanitize the provided URL before executing the navigation. This misconfiguration allows attackers to inject malicious URLs that bypass normal security checks and user verification processes. The vulnerability specifically affects the Android version of Firefox, indicating that the issue lies within platform-specific code paths or mobile browser rendering components that differ from desktop implementations. According to CWE classification, this represents a weakness in input validation and URL handling, potentially falling under CWE-20 for improper input validation or CWE-601 for URL redirection to untrusted sites. The flaw essentially creates a trust boundary violation where user expectations of navigation behavior are subverted by malicious input manipulation.
The operational impact of this vulnerability extends beyond simple navigation confusion to create substantial phishing attack opportunities. Attackers could craft malicious links that appear legitimate but redirect users to fraudulent websites designed to harvest credentials or personal information. The mobile environment amplifies this risk as users may not carefully inspect URLs on smaller screens, and the browser's trust in the original navigation context is compromised. Users might be tricked into believing they are visiting trusted websites while actually being redirected to malicious domains, creating a significant risk for financial transactions, personal data entry, and identity theft. This vulnerability directly relates to ATT&CK technique T1566.001 for spearphishing through email and T1566.002 for spearphishing through social media, where the malicious redirection serves as an attack vector for credential theft and data compromise. The impact is particularly severe given that Firefox for Android represents a significant portion of mobile browser usage, making this vulnerability attractive to threat actors seeking broad reach.
Organizations and users should immediately update to Firefox version 140 or later to remediate this vulnerability, as no effective workarounds exist for the affected versions. System administrators should prioritize this update across mobile device management platforms, particularly in enterprise environments where Firefox for Android is deployed. Security teams should monitor for potential exploitation attempts through phishing campaigns that might leverage this vulnerability, implementing network-based detection measures to identify suspicious URL redirection patterns. Users should be educated about the risks of clicking unknown links and the importance of verifying destination URLs, especially when browsing on mobile devices. The vulnerability highlights the importance of comprehensive testing for mobile browser implementations and the need for robust URL validation mechanisms that prevent unexpected navigation behavior. Given the nature of mobile browsing environments, security professionals should also consider implementing additional layers of protection such as browser isolation techniques or mobile security solutions that can detect and block malicious redirection attempts before they can affect users.