CVE-2026-13957: Google Chrome XSS Vulnerability

CVE-2026-13957 Overview

CVE-2026-13957 is a security vulnerability in Google Chrome caused by incorrect security UI handling in the Extensions component. The flaw affects Chrome versions prior to 150.0.7871.47 and enables universal cross-site scripting (UXSS) when a user is convinced to install a malicious extension. An attacker leveraging a crafted HTML page can inject arbitrary scripts or HTML into the browsing context. Google classifies the Chromium security severity as Medium, and the issue is tracked under [CWE-79] (Improper Neutralization of Input During Web Page Generation).

Critical Impact
Successful exploitation permits arbitrary script or HTML injection across web origins, undermining the browser's same-origin policy for users who install a malicious extension.

Affected Products

Google Chrome versions prior to 150.0.7871.47
Chromium-based browsers sharing the affected extensions code path
Desktop stable channel builds released before the June 2026 update

Discovery Timeline

2026-06-30 - CVE-2026-13957 published to NVD
2026-07-02 - Last updated in NVD database

Technical Details for CVE-2026-13957

Vulnerability Analysis

The vulnerability resides in Chrome's Extensions subsystem, where the browser fails to correctly present or enforce security UI boundaries when an extension renders attacker-controlled HTML content. Because the flaw enables universal cross-site scripting (UXSS), injected scripts can execute in the context of arbitrary origins rather than being confined to the extension's own scope. This breaks the same-origin policy that browsers rely on to isolate web content.

Exploitation requires user interaction and non-trivial conditions. The attacker must first convince the victim to install a malicious extension, then deliver a crafted HTML page that triggers the incorrect UI behavior. Once triggered, the malicious extension can inject arbitrary scripts or HTML into pages the user visits, enabling credential theft, session hijacking, and cross-origin data exfiltration.

Root Cause

The root cause is improper neutralization of input during web page generation within the Extensions component, categorized under [CWE-79]. Chrome's rendering path for extension-driven UI elements does not correctly enforce content boundaries, allowing untrusted markup to be treated as trusted UI. This design defect enables a malicious extension to escape its intended sandbox and act on arbitrary origins.

Attack Vector

The attack vector is network-based but requires user interaction. An attacker publishes or distributes a malicious extension, convinces the user to install it, and then directs the user or the extension to a crafted HTML page. The high attack complexity reflects the multiple preconditions required. Additional technical details are available in the Chromium Issue Tracker #513553557.

Detection Methods for CVE-2026-13957

Indicators of Compromise

Chrome desktop clients running versions earlier than 150.0.7871.47 in the environment
Installation of unknown or unvetted browser extensions from outside the enterprise-managed extension list
Unexpected DOM modifications, injected <script> tags, or inline event handlers appearing on trusted web applications
Outbound requests from browser processes to attacker-controlled domains following extension installation

Detection Strategies

Inventory installed Chrome extensions across managed endpoints and compare against an allow-list of approved IDs
Monitor Chrome version telemetry to identify hosts still running builds prior to 150.0.7871.47
Correlate browser process network telemetry with newly installed extension IDs to surface anomalous behavior

Monitoring Recommendations

Enable Chrome Enterprise reporting to collect extension install events and version data centrally
Alert on installations of extensions with broad host permissions such as <all_urls> or activeTab
Review web application logs for anomalous client-side activity, such as unexpected requests originating from authenticated sessions

How to Mitigate CVE-2026-13957

Immediate Actions Required

Update all Google Chrome desktop installations to version 150.0.7871.47 or later
Audit installed extensions and remove any that are unnecessary or from untrusted publishers
Enforce an extension allow-list via Chrome Enterprise policy to block installation of unvetted extensions
Communicate risk guidance to users, emphasizing that extensions should only be installed from vetted sources

Patch Information

Google addressed CVE-2026-13957 in the Chrome stable channel update to version 150.0.7871.47. Details of the release are published in the Google Chrome Stable Update announcement. Administrators should push the update through managed update channels or rely on Chrome's built-in updater and verify via chrome://settings/help.

Workarounds

Disable or remove non-essential extensions until patched Chrome builds are deployed
Configure the ExtensionInstallAllowlist and ExtensionInstallBlocklist policies to restrict extension installation to approved IDs
Restrict user permissions to prevent installation of extensions from outside the Chrome Web Store on managed devices

bash

# Configuration example
# Chrome Enterprise policy (Windows registry) to restrict extensions
reg add "HKLM\Software\Policies\Google\Chrome\ExtensionInstallBlocklist" /v 1 /t REG_SZ /d "*" /f
reg add "HKLM\Software\Policies\Google\Chrome\ExtensionInstallAllowlist" /v 1 /t REG_SZ /d "<approved-extension-id>" /f