CVE-2026-91709 in Chrome
Summary
by MITRE • 09/16/2026
Type confusion in ServiceWorker in Google Chrome prior to 153.0.8010.47 allowed a remote attacker to execute arbitrary code inside the sandbox via a crafted HTML page. (Chromium security severity: High)
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Analysis
by VulDB Data Team • 09/16/2026
The vulnerability described involves a critical type confusion flaw within the ServiceWorker component of Google Chrome, specifically affecting versions prior to 153.0.8010.47. This issue stems from an improper handling of data types during runtime operations, where the browser fails to correctly distinguish between different object types or memory structures. In complex web environments like those managed by ServiceWorkers, which act as intermediaries for network requests and caching, such misinterpretations can lead to significant security breaches. The core technical flaw lies in the engine's inability to enforce strict type boundaries during specific operations, allowing an attacker to manipulate internal state variables with values of unexpected types. This discrepancy creates a scenario where memory is accessed or modified based on incorrect assumptions about data structure layouts, leading to arbitrary code execution capabilities within the constrained environment of the browser sandbox.
From a technical perspective, this vulnerability aligns closely with CWE-843, which categorizes access to resources using incorrect type conversions. The exploitation mechanism typically involves crafting a malicious HTML page that triggers specific JavaScript interactions designed to confuse the V8 engine or related components responsible for ServiceWorker management. By carefully constructing input data that exploits the type confusion, an attacker can cause the browser to execute code at arbitrary memory addresses. Although Chrome employs multiple layers of defense such as sandboxing and heap hardening techniques like ASLR (Address Space Layout Randomization) and DEP (Data Execution Prevention), a successful exploitation of this high-severity flaw allows bypassing these controls. The result is the execution of arbitrary commands with the privileges granted to the browser process, effectively compromising the integrity of the user's session and potentially leading further into system compromise if other vulnerabilities are chained together.
The operational impact of this vulnerability is severe due to its remote exploitability via a simple crafted HTML page. An attacker does not need physical access or prior authentication; they merely need to lure a victim with vulnerable Chrome versions to visit a malicious site or open an email containing the payload. Once executed, the code runs inside the sandbox, which limits immediate system-wide damage but still poses significant risks including session hijacking, credential theft, and installation of malware within the user's profile directory. The high severity rating assigned by Chromium security teams reflects the ease with which this flaw can be leveraged in real-world attacks, particularly given the widespread use of ServiceWorkers for progressive web applications and background tasks that enhance user experience but also expand the attack surface when vulnerabilities exist.
To mitigate the risks associated with this vulnerability, immediate action is required to update Google Chrome to version 153.0.8010.47 or later where these type checking mechanisms have been corrected. Users should ensure automatic updates are enabled to receive security patches promptly as they become available. For organizations managing multiple endpoints, deploying centralized patch management solutions can help enforce consistent versions across all devices. Additionally, employing browser isolation technologies or restricting the execution of untrusted scripts through content security policies can provide an additional layer of defense against exploitation attempts. Security teams should also monitor for indicators of compromise related to unusual network activity originating from Chrome processes, as this may signal active exploitation efforts targeting systems that have not yet been patched.
This incident underscores the importance of rigorous memory safety practices in browser development and highlights the persistent threat landscape surrounding web technologies. The ATT&CK framework classifies such exploits under techniques involving client-side code injection or remote code execution via vulnerable software components, emphasizing the need for continuous monitoring and rapid response capabilities. By addressing type confusion vulnerabilities promptly, developers and users alike can significantly reduce their exposure to sophisticated cyber threats that leverage browser internals for unauthorized access.