CVE-2026-106354 in Chrome
Summary
by MITRE • 10/07/2026
Improper resource exposure in Extensions in Google Chrome prior to 155.0.8059.39 allowed a remote attacker to obtain cross-origin data via a crafted HTML page. (Chromium security severity: Medium)
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Analysis
by VulDB Data Team • 10/07/2026
The vulnerability identified as an improper resource exposure within the extensions subsystem of Google Chrome, specifically affecting versions prior to 155.0.8059.39, represents a significant breach in the browser's isolation mechanisms. This flaw stems from a failure to correctly enforce access controls when handling resources associated with browser extensions. In modern web browsers, extensions operate within specific security boundaries designed to prevent them from accessing sensitive data belonging to other origins or users unless explicitly permitted by strict permission policies. The defect in question allows an extension, potentially one installed on the victim's machine that has been compromised or is maliciously crafted, to bypass these isolation constraints. By exploiting this improper resource exposure, the extension can read cross-origin data that it should not have access to under normal operational parameters. This type of vulnerability undermines the fundamental trust model of the browser environment, where users rely on the separation between different web contexts to protect their privacy and security.
From a technical perspective, the core issue lies in how Chrome handles resource requests initiated by extensions. Extensions often require access to certain APIs or resources to function correctly, but these accesses must be strictly scoped to prevent data leakage across origin boundaries. The vulnerability indicates that the internal logic governing these scopes failed to validate whether the requested resource belonged to a different origin than the one from which the request originated. Consequently, an attacker who can influence the behavior of an extension through a crafted HTML page or by manipulating extension permissions can trigger this flaw. When such a scenario occurs, the browser incorrectly grants access to sensitive information residing in another domain's context. This could include cookies, local storage data, session tokens, or other personally identifiable information that is typically protected from cross-site scripting and cross-origin read attacks. The severity of this issue is classified as medium by Chromium security standards because while it does not allow for direct code execution on the host system, it facilitates a serious privacy breach and potential account takeover if sensitive authentication data is exfiltrated.
The operational impact of this vulnerability is primarily centered around unauthorized data access and loss of user privacy. A remote attacker can craft an HTML page that interacts with vulnerable extensions to extract cross-origin data without the user's knowledge or consent. This capability enables a range of malicious activities, including session hijacking, where stolen cookies allow the attacker to impersonate the victim on specific websites. It also facilitates targeted phishing campaigns by allowing attackers to gather contextual information about the victim’s browsing habits and stored credentials. Furthermore, this flaw can be chained with other vulnerabilities in extensions or web applications to escalate privileges within the browser environment. For organizations relying on Chrome for secure operations, such as those using managed profiles or enterprise extension policies, this vulnerability poses a risk of data leakage that could violate compliance requirements related to data protection and user privacy. The ability to read cross-origin data effectively neutralizes many of the security guarantees provided by same-origin policy protections within the browser's sandboxed environment.
To mitigate the risks associated with this vulnerability, users must update Google Chrome to version 155.0.8059.39 or later immediately upon availability. This patch addresses the underlying logic errors in resource exposure handling for extensions, ensuring that cross-origin access is properly denied unless explicitly authorized by robust permission checks. In addition to updating the browser, administrators and users should audit installed extensions carefully, removing any that are unnecessary or have excessive permissions beyond what is required for their function. Enabling strict extension policies through group policy management can further restrict which extensions are allowed to run and limit their capabilities. It is also advisable to monitor network traffic and console logs for unusual requests originating from extensions, as this may indicate exploitation attempts in environments where patching cannot be applied immediately. Regular security awareness training regarding the risks of installing unverified or poorly maintained browser add-ons remains a critical component of defense-in-depth strategies against such client-side vulnerabilities.
This vulnerability aligns with CWE-200, which describes exposure of sensitive information to an unauthorized actor, and falls under the broader category of improper access control flaws often categorized as CWE-732 in contexts involving permission misconfiguration. In terms of adversary tactics, this exploit technique corresponds to ATT&CK tactic T1530, Data from Local System, specifically subtechnique T1530.001 which involves data from cloud storage or local file systems accessed via browser extensions. The exploitation vector is classified as remote with low complexity, requiring only a crafted HTML page that the user might visit directly or be tricked into visiting through social engineering. Understanding these classifications helps security teams prioritize remediation efforts and understand the broader threat landscape associated with client-side application vulnerabilities in widely used software like Google Chrome.