CVE-2026-3063: Google Chrome DevTools XSS Vulnerability

CVE-2026-3063 Overview

CVE-2026-3063 is an inappropriate implementation vulnerability in DevTools in Google Chrome prior to version 145.0.7632.116. This security flaw allows an attacker who has convinced a user to install a malicious extension to inject scripts or HTML into a privileged page via DevTools. The vulnerability has been rated with a Chromium security severity of High.

Critical Impact

Attackers can leverage malicious browser extensions to inject unauthorized scripts or HTML content into privileged Chrome DevTools pages, potentially leading to information disclosure and integrity compromise.

Affected Products

• Google Chrome versions prior to 145.0.7632.116
• Google Chrome on Linux
• Google Chrome on Microsoft Windows
• Google Chrome on Apple macOS

Discovery Timeline

• February 23, 2026 - CVE-2026-3063 published to NVD
• February 25, 2026 - Last updated in NVD database

Technical Details for CVE-2026-3063

Vulnerability Analysis

This vulnerability stems from an inappropriate implementation in the Chrome DevTools component. DevTools is a set of web developer tools built directly into the Google Chrome browser that allows developers to inspect, debug, and profile web applications. The flaw exists in how DevTools handles content from browser extensions, failing to properly isolate or sanitize input from extension contexts.

When a user installs a malicious browser extension, that extension can exploit this inappropriate implementation to inject arbitrary scripts or HTML content into privileged DevTools pages. These privileged pages typically have elevated access to browser internals and debugging capabilities that normal web pages cannot access.

The attack requires user interaction—specifically, the user must be convinced to install a malicious extension. Once installed, the extension can leverage the vulnerability to execute scripts within the context of DevTools privileged pages, potentially accessing sensitive debugging information or manipulating the browser's developer interface.

Root Cause

The root cause of CVE-2026-3063 is an inappropriate implementation in how Google Chrome DevTools processes and renders content from browser extensions. The vulnerability allows extension-originated content to be injected into privileged DevTools contexts without proper validation or sandboxing. This represents a failure in the security boundary between extension code and privileged browser components.

Attack Vector

The attack vector for this vulnerability is network-based and requires user interaction. An attacker must first craft a malicious browser extension designed to exploit this vulnerability. The attacker then needs to convince a target user to install this malicious extension—this could be accomplished through social engineering, typosquatting on extension marketplaces, or compromising legitimate extension update mechanisms.

Once the malicious extension is installed and the user opens DevTools, the extension can inject scripts or HTML into the privileged DevTools page. This injected content executes with the privileges of the DevTools context, potentially allowing the attacker to:

• Access sensitive debugging information from web pages the user is inspecting
• Modify the DevTools interface to present misleading information
• Intercept data being analyzed through DevTools
• Potentially leverage DevTools APIs for further exploitation

Detection Methods for CVE-2026-3063

Indicators of Compromise

• Unusual or unauthorized browser extensions installed without user knowledge
• Unexpected script execution or DOM modifications observed within Chrome DevTools pages
• Browser extension activity logs showing interactions with DevTools APIs
• User reports of anomalous DevTools behavior or interface modifications

Detection Strategies

• Monitor for installation of browser extensions from untrusted or unverified sources
• Implement endpoint detection rules to identify extensions attempting to access DevTools privileged contexts
• Review Chrome extension audit logs for suspicious permission requests related to developer tools
• Deploy browser security policies that restrict extension installation to approved sources only

Monitoring Recommendations

• Enable Chrome enterprise policies to log extension installations and updates
• Configure SIEM alerts for unexpected browser extension activity on critical endpoints
• Implement regular audits of installed browser extensions across the enterprise
• Monitor for connections to known malicious extension distribution infrastructure

How to Mitigate CVE-2026-3063

Immediate Actions Required

• Update Google Chrome to version 145.0.7632.116 or later immediately
• Audit all installed browser extensions and remove any untrusted or unnecessary extensions
• Implement browser policies to restrict extension installations to vetted sources only
• Educate users about the risks of installing browser extensions from unknown sources

Patch Information

Google has addressed this vulnerability in Chrome version 145.0.7632.116. Organizations should prioritize updating all Chrome installations to this version or later. For detailed information about the security update, refer to the Google Chrome Update Blog. Additional technical details can be found in the Chromium Issue Tracker #485287859.

Workarounds

• Restrict browser extension installation using Chrome enterprise policies until patching is complete
• Disable DevTools access for users who do not require developer functionality using the DeveloperToolsAvailability policy
• Implement application allowlisting to control which extensions can be installed
• Consider using browser isolation technologies to contain potential exploitation attempts

# Chrome Enterprise Policy Configuration - Restrict Extensions
# Add to Chrome policy template or registry

# Windows Registry path:
# HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Google\Chrome

# Block all extensions except approved ones
ExtensionInstallBlocklist = "*"
ExtensionInstallAllowlist = "approved_extension_id_1,approved_extension_id_2"

# Disable DevTools for non-developer users (0=Disabled, 1=Enabled, 2=Enabled for enterprise users only)
DeveloperToolsAvailability = 2