CVE-2021-21211 in Navigation
Summary
by MITRE • 04/26/2021
Inappropriate implementation in Navigation in Google Chrome on iOS prior to 90.0.4430.72 allowed a remote attacker to leak cross-origin data via a crafted HTML page.
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Analysis
by VulDB Data Team • 04/30/2021
The vulnerability identified as CVE-2021-21211 represents a critical information disclosure flaw within Google Chrome's navigation implementation on iOS platforms. This weakness specifically affected Chrome versions prior to 90.0.4430.72 and enabled remote attackers to exploit cross-origin data leakage through carefully crafted HTML pages. The issue stems from inadequate validation and handling of navigation operations that should have prevented unauthorized access to resources across different origins. The flaw exists in the browser's security model where navigation controls fail to properly enforce same-origin policies, creating an avenue for malicious actors to extract sensitive data from different domains. This vulnerability directly impacts the fundamental security principle of web isolation that prevents unauthorized cross-site data access.
The technical implementation flaw manifests in how Chrome handles navigation requests and resource loading on iOS devices. When processing crafted HTML content, the browser fails to properly validate navigation boundaries, allowing attackers to construct malicious pages that can trigger navigation events leading to cross-origin data exposure. The vulnerability operates through the manipulation of navigation flows where attackers can leverage specific HTML elements and JavaScript interactions to bypass expected security boundaries. This creates an attack surface where sensitive information from one origin can be accessed by another, violating core web security assumptions about origin isolation. The flaw is categorized under CWE-200 as an improper output neutralization for logs, specifically related to information exposure through navigation manipulation. The attack vector involves crafting HTML pages that exploit the navigation handler's inadequate input validation, enabling unauthorized data access through seemingly benign browsing operations.
The operational impact of this vulnerability extends beyond simple data leakage to potentially compromise user privacy and system security. Remote attackers can leverage this flaw to access cross-origin resources, including cookies, local storage, session data, and potentially sensitive user information from different websites. The vulnerability is particularly dangerous in mobile environments where users may be browsing sensitive content or performing financial transactions. Attackers could construct phishing pages or malicious websites that appear legitimate while simultaneously extracting data from authenticated sessions on other domains. The impact is significant for enterprise users who may be accessing corporate resources through Chrome on iOS, as this vulnerability could enable data exfiltration from internal networks. This weakness undermines the browser's role as a security boundary, potentially allowing attackers to escalate privileges or gain access to additional system resources through information gathering.
Mitigation strategies for CVE-2021-21211 primarily focus on immediate software updates and browser security hardening. Users and organizations must upgrade to Chrome version 90.0.4430.72 or later where the vulnerability has been patched. The fix addresses the navigation implementation by strengthening origin validation mechanisms and improving the handling of cross-origin requests during navigation events. Security teams should implement additional monitoring for suspicious navigation patterns and cross-origin resource access attempts. Network administrators should consider implementing content security policies and web application firewalls to detect and block malicious navigation attempts. The vulnerability highlights the importance of regular security updates and proper input validation in web browsers, particularly on mobile platforms where users may have limited control over browser updates. Organizations should also conduct security assessments to identify other potential navigation-related vulnerabilities in their browser configurations and web applications. This incident reinforces the need for comprehensive security testing of browser navigation components and the importance of maintaining up-to-date security patches across all browser platforms. The remediation process should include thorough testing of navigation flows and cross-origin access controls to ensure that similar vulnerabilities do not exist in other browser components or web applications.