CVE-2026-87439 in Chrome
Summary
by MITRE • 09/09/2026
Information leak in ServiceWorker in Google Chrome prior to 153.0.8010.36 allowed a remote attacker who had compromised the renderer process to obtain sensitive information via a crafted HTML page. (Chromium security severity: Medium)
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Analysis
by VulDB Data Team • 09/09/2026
The vulnerability identified as an information leak within the ServiceWorker component of Google Chrome prior to version 153.0.8010.36 represents a significant breach in process isolation boundaries, specifically affecting the renderer processes that handle web content execution. This flaw allows for the unauthorized exfiltration of sensitive data by leveraging the complex interaction between browser services and web applications. The core technical issue stems from improper handling or exposure of internal state within the ServiceWorker API when accessed through maliciously crafted HTML pages. In a typical Chrome architecture, renderer processes are sandboxed to prevent them from accessing privileged information held by other components such as the browser process or network stack. However, this vulnerability indicates that under specific conditions triggered by crafted web content, these isolation mechanisms fail, allowing code running in a compromised renderer context to read data it should not have access to.
From a technical perspective, ServiceWorkers act as proxy servers between web applications and the network, enabling features like offline caching and background synchronization. When an attacker compromises a renderer process through another vulnerability or social engineering tactic, they gain execution privileges within that isolated environment. The flaw in this specific instance allows such compromised code to bypass expected restrictions on accessing sensitive information stored or processed by ServiceWorkers. This could include session tokens, authentication cookies, cached API responses containing personal identifiable information, or other data intended for secure transmission and storage. The severity is classified as medium because while it requires an initial compromise of the renderer process, the resulting impact can be substantial depending on the sensitivity of the leaked data and the context in which the victim was browsing.
The operational impact of this vulnerability extends beyond simple data theft to include potential session hijacking and identity impersonation. If sensitive authentication credentials or tokens are exposed via this information leak, an attacker could use them to authenticate as the legitimate user against backend services. This undermines the confidentiality guarantees provided by modern web browsers and can lead to unauthorized access to private accounts, financial records, or corporate resources. Furthermore, because ServiceWorkers often persist data across browsing sessions, the leaked information might include long-lived tokens that remain valid even after the initial exploit is closed, increasing the window of opportunity for attackers to conduct reconnaissance or lateral movement within affected systems.
This incident aligns with CWE-200, which categorizes Information Exposure as a class of vulnerabilities where sensitive information is disclosed without proper authorization. It also relates to ATT&CK technique T1537, Transfer Data to Cloud Account, if the leaked data is exfiltrated via network requests initiated by the ServiceWorker or associated scripts. The vulnerability highlights the critical importance of maintaining strict separation between untrusted web content and privileged browser services. Mitigation strategies primarily involve updating Google Chrome to version 153.0.8010.36 or later, where these access controls have been reinforced. Additionally, developers should ensure that ServiceWorker scripts do not inadvertently expose internal states through global variables or event handlers accessible from the main thread context unless strictly necessary and properly sanitized. Organizations relying on Chrome for enterprise environments must prioritize patch management to close this gap in their security posture against renderer-based attacks.