CVE-2016-5217 in Chrome
Summary
by MITRE
The extensions API in Google Chrome prior to 55.0.2883.75 for Mac, Windows and Linux, and 55.0.2883.84 for Android incorrectly permitted access to privileged plugins, which allowed a remote attacker to bypass site isolation via a crafted HTML page.
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Analysis
by VulDB Data Team • 05/14/2026
The vulnerability described in CVE-2016-5217 represents a critical privilege escalation flaw within Google Chrome's extensions API implementation across multiple platforms. This security weakness specifically affected Chrome versions prior to 55.0.2883.75 on Mac, Windows, and Linux systems, as well as version 55.0.2883.84 on Android devices. The core issue lies in the improper access control mechanisms that govern how privileged plugins are handled within the browser's extension architecture, creating an avenue for malicious actors to exploit the system's security boundaries.
The technical flaw manifests through the extensions API's failure to properly enforce access restrictions for privileged plugins, allowing remote attackers to craft malicious HTML pages that can bypass Chrome's intended site isolation protections. This vulnerability operates at the intersection of browser security architecture and extension management, where the API should have maintained strict boundaries between user-facing web content and privileged system components. The improper permission handling enables attackers to execute code that would normally be restricted, effectively undermining the browser's security model that separates different origins and processes to prevent cross-site attacks.
From an operational impact perspective, this vulnerability presents a severe threat to user security as it allows remote code execution through seemingly benign web pages. Attackers can leverage this flaw to bypass site isolation mechanisms that are fundamental to modern browser security architectures, potentially enabling them to access sensitive data, perform actions on behalf of users, or escalate privileges within the browser environment. The attack vector requires only a crafted HTML page, making it particularly dangerous as users can be compromised simply by visiting malicious websites without any additional interaction or download requirements.
The vulnerability aligns with CWE-284, which addresses improper access control issues in software systems, and demonstrates characteristics consistent with ATT&CK technique T1059.001 for command and script injection. Organizations should implement immediate mitigations including mandatory Chrome updates to versions 55.0.2883.75 or later, along with enhanced web filtering and monitoring for suspicious HTML content. Network administrators should also consider implementing additional security layers such as content security policies and browser hardening measures to reduce the attack surface. Regular security assessments of browser extensions and their permissions should be conducted to prevent similar privilege escalation scenarios. The incident highlights the importance of maintaining up-to-date browser software and demonstrates how seemingly minor API access control flaws can have significant security implications in complex browser environments.