CVE-2026-106191 in Chrome
Summary
by MITRE • 10/06/2026
Missing authorization in Actor in Google Chrome prior to 155.0.8059.39 allowed a remote attacker who had compromised the renderer process to potentially execute arbitrary code outside the sandbox via a crafted HTML page. (Chromium security severity: Low)
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Analysis
by VulDB Data Team • 10/06/2026
The vulnerability identified as missing authorization in the Actor component of Google Chrome prior to version 155.0.8059.39 represents a critical failure in process isolation mechanisms, which are fundamental to modern browser security architectures. This flaw specifically impacts the Chromium engine's handling of inter-process communication and privilege escalation boundaries within its multi-process architecture. In standard operation, browsers rely on strict sandboxing to confine potentially untrusted content, such as web pages loaded from remote servers, into restricted environments that prevent access to sensitive system resources or arbitrary code execution outside these confined spaces. The Actor component in Chromium is responsible for managing various background tasks and service operations, often requiring higher privileges than the renderer processes that handle page rendering. When authorization checks are omitted or improperly implemented within this actor logic, it creates a pathway for privilege escalation attacks where lower-privilege entities can invoke high-privilege functions without proper validation of their authority to do so.
From a technical perspective, the core issue lies in the insufficient verification of caller identity and permissions when an Actor receives requests from renderer processes. Renderer processes are typically heavily sandboxed to limit the impact of any successful exploitation within web content. However, if an attacker can craft a malicious HTML page that triggers specific interactions with the compromised renderer process, they may exploit this missing authorization check to send commands or data to privileged components like the Actor. Because the system fails to verify whether the requesting entity has legitimate authority to perform the action, it allows the execution of operations intended for trusted internal processes. This effectively bypasses the sandbox boundary, allowing code executed within the renderer context to influence or control parts of the browser that operate with elevated privileges, thereby achieving arbitrary code execution outside the sandbox environment.
The operational impact of this vulnerability is severe due to its potential for remote exploitation via a crafted web page. An attacker does not need physical access to the victim's machine nor do they require prior compromise of other system components; instead, social engineering or drive-by download tactics can be used to lure users into visiting maliciously constructed websites. Once visited, the embedded script exploits the authorization flaw in the Actor component, leading to a complete breach of browser integrity. This results in arbitrary code execution with the privileges of the user running the browser application. Such an outcome enables attackers to install persistent malware, steal sensitive data including cookies and credentials, monitor browsing activity, or use the compromised machine as part of a botnet. The severity is classified as Low by Chromium security standards likely due to the complexity required for exploitation or specific conditions needed, but in practice, any sandbox escape poses significant risk because it undermines the primary defense mechanism against web-based attacks.
This vulnerability aligns with Common Weakness Enumeration (CWE) category CWE-269, which describes Improper Privilege Management, specifically where a principal is granted privileges that are not appropriate for its intended purpose or context. Furthermore, in terms of the MITRE ATT&CK framework, this flaw facilitates techniques associated with Defense Evasion and Privilege Escalation, particularly those involving sandbox escapes such as T1610 Dropbox or more broadly any method allowing code execution outside a controlled environment like T1055 Process Injection if combined with other exploits. The lack of proper authorization checks is a classic example of trusting input from untrusted sources without adequate validation, which violates the principle of least privilege essential for secure software design.
Mitigation strategies primarily involve applying the vendor-provided patch to update Google Chrome to version 155.0.8059.39 or later, where these authorization checks have been reinforced within the Actor component. Organizations should ensure automated deployment mechanisms are in place to keep browsers updated promptly across all endpoints. Additionally, implementing application whitelisting and strict content security policies can help mitigate the impact of such vulnerabilities by restricting what scripts can execute and how they interact with browser internals. Users should also be educated about the risks of visiting untrusted websites and using secure browsing practices that minimize exposure to drive-by download attacks. Regular auditing of third-party extensions is also recommended, as compromised or malicious extensions could potentially leverage similar flaws if present in future versions before patches are applied.