CVE-2026-121085 in Chrome
Summary
by MITRE • 11/03/2026
Incorrect authorization in WebUI in Google Chrome prior to 157.0.8103.38 allowed a remote attacker to bypass system access restrictions into a privileged page via a crafted HTML page. (Chromium security severity: Low)
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Analysis
by VulDB Data Team • 11/03/2026
The vulnerability identified as an incorrect authorization flaw within the WebUI component of Google Chrome prior to version 157.0.8103.38 represents a critical failure in access control mechanisms designed to restrict user interactions with privileged system interfaces. This security deficiency allows remote attackers, who may have limited initial privileges or no direct authentication credentials for specific administrative functions, to bypass established authorization checks. By crafting a malicious HTML page that exploits the misconfigured permission logic within the browser's internal web interface, an attacker can trick the application into executing actions or accessing data intended only for authorized administrators or higher-privilege contexts. This type of vulnerability undermines the fundamental security principle of least privilege, which dictates that users and processes should operate with the minimum levels of access necessary to perform their functions.
From a technical perspective, this flaw likely stems from improper validation of session tokens, missing checks on user roles during API calls initiated by WebUI components, or insufficient separation between public-facing interfaces and administrative endpoints within the browser's architecture. When a crafted HTML page is loaded in an affected version of Chrome, it can send requests to internal APIs that are supposed to be protected but lack robust server-side verification of the requester’s identity or permissions. The Chromium security team has classified this issue with a Low severity rating, which typically indicates that exploitation requires specific conditions such as user interaction or social engineering elements like clicking on a link or visiting a malicious site. However, even low-severity vulnerabilities in widely used software can have significant implications if they lead to privilege escalation within the application context itself.
The operational impact of this vulnerability centers on the potential for unauthorized access to sensitive browser settings, extension management features, or internal diagnostic tools that are not meant for general user consumption. An attacker leveraging this flaw could potentially modify security policies, disable protective features such as Safe Browsing, or extract information stored in privileged areas of the profile directory if those actions are exposed through the WebUI without proper safeguards. While it does not directly grant code execution on the host operating system, compromising these internal controls can serve as a stepping stone for more severe attacks. For instance, an attacker might use this access to install malicious extensions that persist across sessions or alter network settings to facilitate man-in-the-middle attacks against other browsing activities conducted by the user.
This incident aligns with Common Weakness Enumeration (CWE) category CWE-269, which describes Improper Privilege Assignment, and specifically relates to scenarios where an actor is able to access resources that are not intended for them due to flawed authorization logic. In terms of the MITRE ATT&CK framework, this vulnerability facilitates techniques associated with Initial Access through spearphishing links or drive-by downloads, followed by Defense Evasion as the attacker manipulates browser settings to avoid detection. It also touches upon Persistence if malicious configurations allow long-term control over the browsing environment. The existence of such flaws highlights the complexity inherent in maintaining secure boundaries between different trust levels within complex software applications like web browsers that integrate numerous subsystems and interfaces.
Mitigation strategies primarily involve updating Google Chrome to version 157.0.8103.38 or later, where these authorization checks have been corrected and hardened against exploitation attempts. Organizations should enforce automated patch management policies to ensure all endpoints are running the latest stable release of the browser, thereby closing this specific attack vector immediately. Additionally, implementing strict Content Security Policies (CSP) can help mitigate some risks by restricting how scripts interact with internal resources, although relying solely on client-side defenses is insufficient given that the flaw exists in the application logic itself. Users should remain vigilant against visiting untrusted websites and avoid downloading HTML files from unknown sources, as these are common vectors for triggering such crafted exploits. Regular security audits of browser configurations and monitoring for anomalous changes to privileged settings can also provide early warning indicators of potential exploitation attempts targeting similar weaknesses.