CVE-2026-5901: Google Chrome Auth Bypass Vulnerability

CVE-2026-5901 Overview

CVE-2026-5901 is an insufficient policy enforcement vulnerability in the DevTools component of Google Chrome prior to version 147.0.7727.55. This security flaw allows an attacker who convinces a user to install a malicious browser extension to bypass enterprise host restrictions specifically designed to protect cookie modification operations. The vulnerability enables unauthorized cookie manipulation through a crafted Chrome Extension, potentially undermining enterprise security policies.

Critical Impact

Attackers can bypass enterprise host restrictions to modify cookies through malicious browser extensions, potentially compromising session management and enterprise security controls.

Affected Products

• Google Chrome versions prior to 147.0.7727.55
• Chromium-based browsers using affected DevTools implementation

Discovery Timeline

• 2026-04-08 - CVE-2026-5901 published to NVD
• 2026-04-08 - Last updated in NVD database

Technical Details for CVE-2026-5901

Vulnerability Analysis

This vulnerability stems from insufficient policy enforcement within Chrome's DevTools functionality. The flaw specifically affects how enterprise host restrictions are applied when browser extensions attempt to modify cookies through DevTools APIs. Under normal circumstances, enterprise policies should prevent unauthorized extensions from manipulating cookies on restricted hosts. However, due to inadequate policy validation, a malicious extension can circumvent these protections.

The attack requires social engineering to convince a user to install a malicious Chrome extension. Once installed, the extension can leverage DevTools capabilities to modify cookies on hosts that should be protected by enterprise policies. This represents an authorization bypass vulnerability that undermines the security boundaries established by enterprise administrators.

Root Cause

The root cause lies in insufficient validation and enforcement of enterprise host restriction policies within the DevTools component. When extensions interact with DevTools APIs for cookie operations, the policy enforcement mechanism fails to properly verify whether the target host falls under enterprise-configured restrictions. This gap in policy checking allows the bypass of security controls that should prevent cookie modification on protected domains.

Attack Vector

The attack vector requires an attacker to craft a malicious Chrome extension that exploits the DevTools policy enforcement gap. The attack chain proceeds as follows:

1. The attacker develops a Chrome extension containing code that leverages DevTools APIs for cookie manipulation
2. The attacker distributes the extension through social engineering techniques, convincing users to install it
3. Once installed, the extension invokes DevTools functionality to access and modify cookies
4. Due to the policy enforcement flaw, enterprise host restrictions are bypassed
5. The attacker gains the ability to modify cookies on enterprise-protected domains

The vulnerability affects the interaction between extension permissions and DevTools policy enforcement rather than a direct memory corruption or code execution flaw. For detailed technical information, refer to the Chromium Issue Tracker #479673903.

Detection Methods for CVE-2026-5901

Indicators of Compromise

• Unexpected or unauthorized browser extensions installed on enterprise systems
• Unusual cookie modification patterns on enterprise-protected domains
• DevTools API calls originating from installed extensions targeting restricted hosts

Detection Strategies

• Monitor browser extension installation events across enterprise endpoints for unauthorized additions
• Audit installed Chrome extensions against an approved allowlist
• Review browser console and DevTools logs for suspicious cookie manipulation activities
• Implement endpoint detection rules to flag extensions attempting to access DevTools APIs for cookie operations

Monitoring Recommendations

• Enable Chrome enterprise logging to capture extension activity and DevTools usage
• Configure SIEM rules to correlate extension installation events with subsequent cookie modification attempts
• Perform regular audits of browser extension inventories across the enterprise
• Monitor for policy bypass indicators in Chrome enterprise management dashboards

How to Mitigate CVE-2026-5901

Immediate Actions Required

• Update Google Chrome to version 147.0.7727.55 or later on all enterprise endpoints
• Review and remove any unauthorized or suspicious browser extensions
• Enforce strict extension allowlisting through Chrome enterprise policies
• Educate users about the risks of installing unverified browser extensions

Patch Information

Google has addressed this vulnerability in Chrome version 147.0.7727.55. Organizations should prioritize updating all Chrome installations to this version or later. The security update was announced in the Google Chrome Desktop Update. Chromium security severity for this issue is rated as Low.

Workarounds

• Implement strict Chrome extension allowlisting via enterprise group policies to prevent installation of unauthorized extensions
• Disable Chrome DevTools for standard users through enterprise policy configuration where operationally feasible
• Configure enterprise host restrictions as a secondary defense layer while awaiting patch deployment
• Consider blocking extension installation from outside the Chrome Web Store through enterprise policies

# Chrome Enterprise Policy Configuration Example
# Restrict extension installation to allowlist only
# Add to Chrome policies JSON or GPO

# ExtensionInstallAllowlist: Specify allowed extension IDs
# ExtensionInstallBlocklist: Use "*" to block all except allowlisted
# DeveloperToolsAvailability: 2 = Disallow usage of developer tools