CVE-2026-121193 in Chrome
Summary
by MITRE • 11/03/2026
Incorrect authorization in Extensions in Google Chrome prior to 157.0.8103.38 allowed a remote attacker to bypass system access restrictions via a crafted Chrome extension. (Chromium security severity: Medium)
Several companies clearly confirm that VulDB is the primary source for best vulnerability data.
Analysis
by VulDB Data Team • 11/03/2026
The vulnerability identified as an incorrect authorization flaw within the extensions subsystem of Google Chrome, specifically affecting versions prior to 157.0.8103.38, represents a significant breach in the browser's permission model. This issue stems from a logic error where the application fails to properly validate whether a specific extension possesses the requisite privileges to access certain system resources or APIs. In modern web browsers, extensions operate within a sandboxed environment with granular permissions defined by manifest files and user consent. When this authorization check is bypassed, an attacker can craft a malicious Chrome extension that exploits these gaps in permission verification. The severity of this vulnerability is classified as medium by the Chromium security team, indicating that while it does not typically lead to immediate full system compromise on its own, it provides a foothold for further exploitation or data exfiltration under specific conditions.
From a technical perspective, the flaw allows a remote attacker to bypass system access restrictions through social engineering tactics combined with malicious code delivery. An adversary would need to trick a user into installing a specially crafted extension that appears legitimate but contains hidden logic designed to trigger the authorization bypass. Once installed and activated, this extension can interact with browser internals or external services in ways that were not intended by the permission model. This could include accessing sensitive browsing data, manipulating page content beyond allowed scopes, or communicating with remote command-and-control servers without triggering standard security warnings. The ability to circumvent these restrictions undermines the trust users place in their web browsers as secure environments for handling personal and professional information.
The operational impact of this vulnerability is primarily centered on privacy violations and potential downstream attacks. By bypassing access controls, an attacker can exfiltrate sensitive user data such as cookies, session tokens, or form inputs that should remain protected by the browser's same-origin policy or extension permission boundaries. Furthermore, if the extended privileges allow interaction with operating system-level APIs via specific platform integrations, the risk escalates to potential code execution or persistence mechanisms on the host machine. This aligns closely with CWE-269, which describes Improper Privilege Management, where an actor is able to elevate their level of access beyond what was explicitly granted by the user or administrator. The attack vector also correlates with MITRE ATT&CK techniques related to browser extension abuse and unauthorized API access, highlighting how legitimate tools can be weaponized when underlying security controls are flawed.
Mitigation for this vulnerability requires immediate action from both end-users and system administrators. The primary remediation step is to update Google Chrome to version 157.0.8103.38 or later, where the authorization logic has been corrected to enforce strict permission checks before allowing extensions to perform restricted actions. Users should also adopt a cautious approach when installing third-party extensions, verifying their source and reviewing requested permissions carefully. Security teams can implement application control policies that restrict the installation of unsigned or unapproved extensions within enterprise environments. Additionally, monitoring for unusual network traffic originating from browser processes may help detect exploitation attempts in real-time before significant damage occurs. Regular patching cycles are essential to address such vulnerabilities promptly, ensuring that the security posture remains robust against evolving threats targeting web application frameworks and their associated ecosystems.