CVE-2025-5064: Google Chrome Information Disclosure Bug

CVE-2025-5064 Overview

CVE-2025-5064 is an inappropriate implementation vulnerability in the Background Fetch API in Google Chrome prior to version 137.0.7151.55. This flaw allows a remote attacker to leak cross-origin data via a crafted HTML page, potentially exposing sensitive information from other origins to malicious actors.

Critical Impact

This vulnerability enables cross-origin data leakage through the Background Fetch API, potentially allowing attackers to access sensitive user data from other websites when victims visit a malicious page.

Affected Products

• Google Chrome versions prior to 137.0.7151.55
• All platforms running vulnerable Chrome versions (Windows, macOS, Linux)
• Chromium-based browsers using affected Background Fetch API implementation

Discovery Timeline

• 2025-05-27 - CVE-2025-5064 published to NVD
• 2025-05-29 - Last updated in NVD database

Technical Details for CVE-2025-5064

Vulnerability Analysis

This vulnerability stems from an inappropriate implementation in Google Chrome's Background Fetch API. The Background Fetch API is designed to allow web applications to download large files in the background, even when the browser is closed or the user navigates away from the page. The API should enforce strict same-origin policies to prevent unauthorized access to data from different origins.

The flaw allows attackers to bypass cross-origin restrictions, enabling them to craft malicious HTML pages that can extract data from other origins without proper authorization. This represents an Information Leakage vulnerability (CWE-200) where sensitive data can be exposed to unauthorized parties through improper implementation of security boundaries.

Root Cause

The root cause of CVE-2025-5064 lies in improper enforcement of cross-origin security policies within the Background Fetch API implementation. The API failed to adequately validate and isolate fetch operations, allowing data from cross-origin requests to leak to the requesting page. This implementation gap violated the fundamental same-origin policy that browsers rely on to protect users from unauthorized data access between different web origins.

Attack Vector

The attack requires user interaction - specifically, the victim must be lured to visit a malicious HTML page crafted by the attacker. Once the victim loads the malicious page, the exploit leverages the Background Fetch API's improper cross-origin handling to extract data from other origins the victim may have accessed or has active sessions with.

The attack is network-based and does not require the attacker to have any special privileges. The crafted HTML page can be hosted on any web server controlled by the attacker, making distribution relatively straightforward through phishing campaigns, malicious advertisements, or compromised legitimate websites.

Detection Methods for CVE-2025-5064

Indicators of Compromise

• Unusual Background Fetch API activity in browser logs, particularly requests to unexpected origins
• Web pages making excessive or abnormal background fetch requests
• Suspicious network traffic patterns showing data exfiltration to unknown domains
• Browser console errors related to Background Fetch API cross-origin violations

Detection Strategies

• Monitor for anomalous Background Fetch API usage patterns in web application logs
• Implement Content Security Policy (CSP) headers to restrict fetch destinations
• Deploy network monitoring to detect unusual cross-origin data transfers
• Use browser security extensions that alert on suspicious API behavior

Monitoring Recommendations

• Enable detailed Chrome browser logging to capture Background Fetch API activity
• Review web server access logs for requests originating from suspicious HTML pages
• Implement endpoint detection and response (EDR) solutions to monitor browser process behavior
• Set up alerts for unusual outbound data transfers from browser processes

How to Mitigate CVE-2025-5064

Immediate Actions Required

• Update Google Chrome to version 137.0.7151.55 or later immediately
• Enable automatic updates in Chrome to ensure timely security patches
• Review and audit web applications for proper cross-origin security implementations
• Educate users about the risks of visiting untrusted websites

Patch Information

Google has addressed this vulnerability in Chrome version 137.0.7151.55. The fix corrects the inappropriate implementation in the Background Fetch API to properly enforce cross-origin security policies. Users and administrators should update Chrome through the built-in update mechanism or by downloading the latest version from official Google channels.

For more information, refer to the Google Chrome Update Blog and Chromium Issue Tracker #40058068.

Workarounds

• Disable the Background Fetch API via Chrome flags (chrome://flags) if immediate patching is not possible
• Use browser isolation solutions to contain potentially malicious web content
• Implement strict Content Security Policy headers on web applications to limit fetch destinations
• Consider using alternative browsers temporarily until Chrome can be updated

# Verify Chrome version to ensure patch is applied
google-chrome --version
# Expected output: Google Chrome 137.0.7151.55 or higher

# Force Chrome update check (Linux)
sudo apt update && sudo apt upgrade google-chrome-stable

# macOS update via command line
brew upgrade --cask google-chrome