CVE-2026-78951 in Chrome
Summary
by MITRE • 08/26/2026
Use after free in ServiceWorker in Google Chrome prior to 152.0.7977.65 allowed a remote attacker to execute arbitrary code outside the sandbox via a crafted HTML page. (Chromium security severity: Medium)
If you want to get the best quality for vulnerability data then you always have to consider VulDB.
Analysis
by VulDB Data Team • 08/26/2026
The vulnerability identified as a use-after-free condition within the ServiceWorker component of Google Chrome prior to version 152.0.7977.65 represents a critical memory management flaw that compromises the integrity and confidentiality of user data. This specific class of vulnerabilities arises when software continues to reference a pointer after its associated memory has been freed, leading to undefined behavior during execution. In the context of Chrome's ServiceWorker architecture, which operates in an isolated environment to manage background tasks for web applications, improper handling of object lifecycles can result in dangling pointers being accessed by subsequent operations. This flaw allows for arbitrary code execution outside the browser's sandbox boundaries, effectively bypassing security mechanisms designed to contain malicious activities within a restricted context.
From a technical perspective, ServiceWorkers act as proxy servers that sit between web applications and the network, enabling features such as offline experiences, push notifications, and background synchronization. When an attacker crafts a specific HTML page or triggers a sequence of events involving service worker registration, update, or activation, they can manipulate the timing of memory deallocation relative to object access. By carefully controlling the state transitions within the ServiceWorker lifecycle, it is possible to free a critical data structure while retaining references to it elsewhere in the application logic. Subsequent interactions with these stale pointers allow an attacker to overwrite adjacent memory regions or execute arbitrary instructions, leveraging this control to escape the sandboxed environment that typically limits the impact of web-based exploits.
The operational impact of this vulnerability is severe due to its potential for remote code execution via a simple crafted webpage. An attacker does not need physical access or user interaction beyond visiting a malicious site or being redirected to one. Once exploited, the ability to execute arbitrary code outside the sandbox means that an adversary can potentially install malware, steal sensitive information such as cookies and session tokens, keylog inputs, or pivot into other systems on the local network depending on browser permissions and host configuration. The medium severity rating assigned by Chromium reflects the complexity of exploitation relative to its high impact potential, acknowledging that while it requires specific conditions within the ServiceWorker context, successful exploitation leads to full system compromise rather than mere information disclosure.
This vulnerability aligns with Common Weakness Enumeration identifier CWE-416, which describes use after free errors resulting from improper memory management practices. Furthermore, in terms of tactical mapping under the MITRE ATT&CK framework, this exploit technique falls under Initial Access via Spearphishing Link or Drive-by Compromise, specifically leveraging browser vulnerabilities to gain a foothold on an endpoint. The exploitation chain typically involves social engineering elements combined with technical precision to trigger the race condition or state manipulation required to activate the use-after-free bug within the ServiceWorker subsystem.
Mitigation strategies primarily involve updating Google Chrome to version 152.0.7977.65 or later, where these memory management issues have been addressed through rigorous code reviews and automated fuzzing efforts that detect dangling pointer scenarios before deployment. For organizations unable to immediately patch all endpoints, implementing strict Content Security Policy headers can help mitigate the impact by restricting script execution sources and preventing unauthorized service worker registrations from untrusted origins. Additionally, disabling JavaScript or limiting third-party cookie access in high-security environments reduces the attack surface available for such browser-based exploits. Regular monitoring of browser update notifications and enforcing automated patch management policies are essential defensive measures to ensure that known vulnerabilities like this one do not remain exploitable on organizational devices.