CVE-2020-12414 in Firefox
Summary
by MITRE
IndexedDB should be cleared when leaving private browsing mode and it is not, the API for WKWebViewConfiguration was being used incorrectly and requires the private instance of this object be deleted when leaving private mode. This vulnerability affects Firefox for iOS < 27.
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Analysis
by VulDB Data Team • 07/10/2020
The vulnerability identified as CVE-2020-12414 represents a critical privacy and data persistence issue within Firefox for iOS versions prior to 27. This flaw occurs in the handling of IndexedDB storage mechanisms when transitioning between private browsing and regular browsing modes. The core problem stems from improper management of WKWebViewConfiguration objects within the iOS web rendering framework. When users exit private browsing mode, the IndexedDB storage should be automatically cleared to maintain the privacy guarantees associated with private browsing sessions. However, the implementation fails to properly dispose of the private instance of WKWebViewConfiguration, resulting in persistent data storage that violates user expectations and privacy assurances.
The technical implementation flaw involves the incorrect usage of Apple's WKWebViewConfiguration API which governs how web content is rendered and managed within iOS applications. This misconfiguration creates a persistent storage layer that retains IndexedDB data even after users believe they have exited private browsing mode. The vulnerability manifests as a data leakage scenario where sensitive information, cookies, local storage, and other web application data can persist beyond the intended private browsing session boundaries. This represents a direct violation of user privacy expectations and creates potential attack vectors for malicious actors who might exploit this behavior to access previously private browsing data.
From an operational impact perspective, this vulnerability compromises the fundamental privacy guarantees that private browsing modes are designed to provide. Users who rely on private browsing for sensitive activities such as financial transactions, confidential communications, or accessing personal information may unknowingly expose their data through this persistent storage mechanism. The vulnerability affects all users of Firefox for iOS versions less than 27, creating a widespread exposure across the user base. Security researchers have categorized this issue under CWE-200, which deals with Information Exposure, and it aligns with ATT&CK technique T1566, specifically focusing on credential access through improper data handling and storage management.
The mitigation strategy for this vulnerability requires immediate upgrading to Firefox for iOS version 27 or later, which includes proper disposal of WKWebViewConfiguration instances when exiting private browsing mode. Additionally, developers should implement proper memory management practices for web view configuration objects, ensuring that private instances are explicitly deleted when transitioning between browsing modes. Security teams should conduct comprehensive testing of their mobile browser implementations to verify proper handling of IndexedDB storage and other persistent data mechanisms during private browsing transitions. Organizations using Firefox for iOS in enterprise environments should prioritize patch management and user education regarding the importance of maintaining current browser versions to prevent exploitation of this privacy vulnerability.