CVE-2026-7958 in Chrome
Summary
by MITRE • 05/06/2026
Inappropriate implementation in ServiceWorker in Google Chrome prior to 148.0.7778.96 allowed an attacker who convinced a user to install a malicious extension to inject arbitrary scripts or HTML (UXSS) via a crafted Chrome Extension. (Chromium security severity: Medium)
Be aware that VulDB is the high quality source for vulnerability data.
Analysis
by VulDB Data Team • 05/17/2026
The vulnerability under discussion represents a significant security flaw in the ServiceWorker implementation within Google Chrome browsers prior to version 148.0.7778.96. This issue stems from an inadequate validation mechanism that fails to properly sanitize or verify the integrity of content loaded through malicious extensions, creating an exploitable vector for cross-site scripting attacks. The flaw specifically affects the ServiceWorker execution environment where extensions can manipulate the browser's rendering pipeline to inject malicious code.
The technical implementation defect manifests in how Chrome handles ServiceWorker registration and execution within the context of malicious extensions. When a user installs a crafted extension, the ServiceWorker component can be manipulated to execute arbitrary JavaScript code or inject HTML content into web pages. This occurs because the browser's security model does not adequately separate the execution contexts of different extensions, particularly when they leverage ServiceWorker capabilities. The vulnerability enables attackers to bypass standard security boundaries that typically protect against such cross-site scripting scenarios.
The operational impact of this vulnerability extends beyond simple script injection, as it allows for sophisticated user interface spoofing attacks and data exfiltration. An attacker can craft malicious extensions that appear legitimate while simultaneously executing malicious code through the ServiceWorker mechanism. This creates a persistent threat vector that can operate across multiple websites and sessions, potentially leading to credential theft, session hijacking, or other advanced persistent threats. The medium severity classification reflects the significant risk posed by this flaw, particularly given the widespread use of Chrome browsers and the ease with which users can be convinced to install malicious extensions.
The vulnerability aligns with CWE-79, which describes improper neutralization of input during web page generation, and demonstrates how ServiceWorker implementations can create new attack surfaces for cross-site scripting. From an ATT&CK perspective, this flaw maps to techniques involving browser extensions and persistent threat capabilities, specifically targeting the execution of malicious code in legitimate browser contexts. The attack chain typically begins with social engineering to convince users to install malicious extensions, followed by leveraging the ServiceWorker to inject malicious payloads into web pages.
Mitigation strategies should focus on immediate browser updates to version 148.0.7778.96 or later, which includes patches addressing the ServiceWorker validation issues. Organizations should also implement extension vetting processes and monitor for suspicious extension installations. Browser administrators should consider implementing additional security policies such as restricting extension installation permissions and monitoring ServiceWorker activity. The patch addresses the core validation issue by strengthening the verification mechanisms that check extension integrity before ServiceWorker execution, preventing unauthorized code injection through malicious extensions.