CVE-2025-8576: Google Chrome Use After Free Vulnerability

CVE-2025-8576 Overview

CVE-2025-8576 is a use-after-free vulnerability in the Extensions component of Google Chrome versions prior to 139.0.7258.66. A remote attacker can trigger heap corruption by convincing a user to install or interact with a crafted Chrome extension. Successful exploitation can lead to arbitrary code execution within the affected browser process. The flaw is tracked under CWE-416 and impacts Chrome across Windows, macOS, and Linux platforms. Google addressed the issue in the Stable channel update published in August 2025.

Critical Impact

Remote attackers can achieve heap corruption and potential code execution in the browser process through a malicious Chrome extension, requiring only user interaction.

Affected Products

• Google Chrome prior to 139.0.7258.66 on Microsoft Windows
• Google Chrome prior to 139.0.7258.66 on Apple macOS
• Google Chrome prior to 139.0.7258.66 on Linux

Discovery Timeline

• 2025-08-07 - CVE-2025-8576 published to the National Vulnerability Database (NVD)
• 2025-11-13 - Last updated in NVD database

For vendor details, see the Google Chrome Desktop Update and the Chromium Issue Tracker Entry.

Technical Details for CVE-2025-8576

Vulnerability Analysis

The vulnerability resides in the Extensions subsystem of the Chromium browser. A use-after-free condition occurs when the Extensions component continues to reference heap memory that has already been released. An attacker who controls the contents and behavior of a Chrome Extension can shape allocator state to reclaim the freed region with attacker-controlled data. When the dangling pointer is dereferenced, the corrupted object can be used to influence control flow or read and write attacker-chosen memory.

Exploitation requires user interaction, typically installing or invoking the malicious extension. The attack vector is network-based because extensions can be distributed through web channels and extension marketplaces. Successful exploitation provides high impact to confidentiality, integrity, and availability within the browser sandbox boundary.

Root Cause

The root cause is improper object lifetime management within the Extensions code path. The component releases a heap object while another reference remains live, producing a stale pointer. This pattern is classified as CWE-416, Use After Free.

Attack Vector

An attacker publishes or sideloads a crafted Chrome Extension. When a victim installs or interacts with the extension, the extension triggers the vulnerable code path. The extension then manipulates heap layout to control the contents of the freed allocation. Subsequent use of the dangling reference enables heap corruption and potential renderer-level code execution.

No verified public proof-of-concept code is available. See the Chromium Issue Tracker Entry for further technical detail when access is granted.

Detection Methods for CVE-2025-8576

Indicators of Compromise

• Chrome processes crashing with heap corruption signatures or SIGSEGV during extension load or activation.
• Unexpected Chrome extensions installed outside of standard organizational policy or the Chrome Web Store allowlist.
• Renderer or extension utility processes spawning unusual child processes or making anomalous outbound network connections.

Detection Strategies

• Inventory installed Chrome extensions across endpoints and compare against an approved allowlist.
• Monitor Chrome version telemetry to identify hosts running builds prior to 139.0.7258.66.
• Hunt for crash dumps and Windows Error Reporting (WER) artifacts tied to chrome.exe extension threads.

Monitoring Recommendations

• Forward browser telemetry, extension install events, and process creation logs to a central analytics platform for correlation.
• Alert on extensions loaded from developer mode or unpacked sources on managed endpoints.
• Track outbound connections from Chrome utility processes to low-reputation domains.

How to Mitigate CVE-2025-8576

Immediate Actions Required

• Update Google Chrome to version 139.0.7258.66 or later on all Windows, macOS, and Linux endpoints.
• Restart Chrome on every endpoint after the update to ensure the patched binary is loaded into memory.
• Audit installed extensions and remove any that are unsigned, unused, or untrusted.

Patch Information

Google released the fix in the Stable channel update for desktop on August 5, 2025. Apply the update referenced in the Google Chrome Desktop Update advisory. Enterprises managing Chrome through Group Policy or Workspace should validate that auto-update is enabled and that the deployed channel reflects 139.0.7258.66 or higher.

Workarounds

• Enforce an extension allowlist using the ExtensionInstallAllowlist and ExtensionInstallBlocklist policies until patching is complete.
• Disable developer mode and block installation of unpacked extensions through enterprise policy.
• Restrict extension installation to administrators on managed devices to reduce user-driven exposure.

# Example Chrome enterprise policy (Linux JSON policy file)
# /etc/opt/chrome/policies/managed/extension_controls.json
{
  "ExtensionInstallBlocklist": ["*"],
  "ExtensionInstallAllowlist": [
    "<approved-extension-id-1>",
    "<approved-extension-id-2>"
  ],
  "DeveloperToolsAvailability": 2,
  "ExtensionInstallSources": ["https://chrome.google.com/webstore/*"]
}