CVE-2025-3066: Google Chrome Use After Free Vulnerability

CVE-2025-3066 Overview

CVE-2025-3066 is a use-after-free vulnerability in the Site Isolation component of Google Chrome before version 135.0.7049.84. A remote attacker can trigger heap corruption by serving a crafted HTML page to a user. The flaw is tracked under CWE-416: Use After Free and was rated High severity by the Chromium security team.

Successful exploitation requires user interaction, typically loading a malicious page in a vulnerable browser. The vulnerability affects Chrome on all desktop platforms shipped through the Stable channel before the April 2025 update.

Critical Impact

A remote attacker can corrupt heap memory in the browser process via a crafted HTML page, potentially leading to arbitrary code execution within the renderer or sandbox-bridging components tied to Site Isolation.

Affected Products

• Google Chrome versions prior to 135.0.7049.84 on Windows, macOS, and Linux
• Chromium-based browsers that incorporate the affected Site Isolation code before the upstream fix
• Embedded applications using outdated Chromium builds with Site Isolation enabled

Discovery Timeline

• 2025-04-02 - CVE-2025-3066 published to NVD
• 2025-04-08 - Last updated in NVD database

Technical Details for CVE-2025-3066

Vulnerability Analysis

The vulnerability resides in Chrome's Site Isolation feature, which separates web content from different origins into distinct renderer processes. A use-after-free condition occurs when code retains a reference to a Site Isolation object after that object has been freed. When the dangling pointer is later dereferenced, the attacker-controlled heap state determines program behavior, enabling heap corruption.

Heap corruption in this context can lead to type confusion, control of virtual function tables, or arbitrary read and write primitives. Combined with a sandbox escape, the bug could allow code execution outside the renderer process. Site Isolation handles cross-origin boundaries and frame lifecycle events, which historically have been a source of object-lifetime errors in Chromium.

Exploitation requires the victim to load attacker-controlled HTML, typically through navigation, embedded frames, or malvertising. The Chromium project addressed the issue in the Stable channel update referenced in the Google Chrome Stable Update advisory.

Root Cause

The root cause is improper object lifetime management within Site Isolation code paths. A reference to a Site Isolation-managed object outlives the allocation, producing a dangling pointer. Subsequent operations dereference freed memory, which an attacker can groom to control program state.

Attack Vector

The attack vector is network-based and requires user interaction. An attacker hosts a crafted HTML page and lures a victim to visit it, or delivers the payload through compromised sites, ad networks, or embedded iframes. No authentication is required, and the renderer processes the malicious content automatically.

No verified public exploit code is available. Technical specifics are restricted in the Chromium Issue Tracker Entry pending broader patch adoption.

Detection Methods for CVE-2025-3066

Indicators of Compromise

• Chrome renderer or browser process crashes with heap corruption signatures shortly after navigation to an untrusted page
• Unexpected child process creation from chrome.exe following web browsing activity
• Outbound connections from Chrome processes to newly registered or low-reputation domains hosting HTML payloads

Detection Strategies

• Inventory installed Chrome versions across the fleet and flag any instance below 135.0.7049.84
• Monitor endpoint telemetry for browser process crashes correlated with specific URLs in browsing history
• Correlate web proxy logs with threat intelligence feeds for malicious HTML delivery infrastructure

Monitoring Recommendations

• Track Chrome version distribution through software inventory and patch management systems
• Alert on anomalous process trees rooted in browser processes, such as shell or scripting engines spawned by chrome.exe
• Capture and retain crash dumps from browser processes to support post-incident analysis

How to Mitigate CVE-2025-3066

Immediate Actions Required

• Update Google Chrome to version 135.0.7049.84 or later on all Windows, macOS, and Linux endpoints
• Restart browsers after updating to ensure the patched binaries are loaded into memory
• Audit Chromium-based applications and embedded browsers for the vulnerable code and apply vendor updates

Patch Information

Google released the fix in the Stable channel update for desktop. Administrators should deploy Chrome 135.0.7049.84 or newer using enterprise update mechanisms. Details are available in the Google Chrome Stable Update release notes.

Workarounds

• Enforce automatic Chrome updates through enterprise policy to reduce exposure windows
• Restrict browsing to trusted sites using web filtering and DNS-based protections until patches are deployed
• Disable or limit third-party content rendering through Content Security Policy and ad-blocking controls on managed endpoints