CVE-2026-6304: Google Chrome Graphite Use-After-Free

CVE-2026-6304 Overview

CVE-2026-6304 is a use-after-free vulnerability affecting the Graphite component in Google Chrome versions prior to 147.0.7727.101. This memory corruption flaw exists in the browser's font rendering subsystem and can be exploited by a remote attacker who has already compromised the renderer process. Successful exploitation could allow the attacker to escape the Chrome sandbox through a specially crafted HTML page, potentially leading to arbitrary code execution with elevated privileges on the victim's system.

Critical Impact

This vulnerability enables sandbox escape from a compromised renderer process, allowing attackers to break out of Chrome's security boundaries and execute code with higher privileges on the underlying system.

Affected Products

• Google Chrome versions prior to 147.0.7727.101
• Chromium-based browsers using vulnerable Graphite component versions
• Desktop platforms (Windows, macOS, Linux) running affected Chrome versions

Discovery Timeline

• April 15, 2026 - CVE-2026-6304 published to NVD
• April 15, 2026 - Last updated in NVD database

Technical Details for CVE-2026-6304

Vulnerability Analysis

This use-after-free vulnerability (CWE-416) resides in the Graphite component of Google Chrome, which handles advanced font rendering and shaping for complex scripts. The flaw occurs when memory that has been freed is subsequently accessed during font processing operations, creating a dangling pointer scenario.

The vulnerability requires an attacker to have already compromised the renderer process, making this part of a potential exploit chain. From the compromised renderer, an attacker can craft specific inputs that trigger the use-after-free condition in Graphite, ultimately allowing escape from Chrome's sandbox isolation. The sandbox is a critical security boundary that normally prevents compromised renderer processes from accessing system resources.

While exploitation requires high attack complexity due to the prerequisite of renderer compromise and user interaction (visiting a malicious page), the changed scope impact means successful exploitation affects resources beyond the vulnerable component's security context.

Root Cause

The root cause is improper memory management in the Graphite font rendering library. When processing certain font data structures, the code fails to properly track object lifetimes, leading to a scenario where memory is freed but references to that memory remain active. Subsequent operations that use these stale references trigger the use-after-free condition.

This type of vulnerability typically arises from complex object ownership patterns in font shaping code, where multiple components may hold references to shared memory regions. When deallocation occurs without properly invalidating all references, the stage is set for exploitation.

Attack Vector

The attack requires network access and user interaction. An attacker must first compromise the Chrome renderer process through a separate vulnerability, then leverage CVE-2026-6304 to escape the sandbox. The attack flow involves:

1. User visits an attacker-controlled or compromised website
2. Malicious content exploits a separate vulnerability to gain renderer process control
3. Attacker uses crafted HTML/font data to trigger the use-after-free in Graphite
4. Successful exploitation breaks out of the sandbox, escalating privileges

The vulnerability is triggered through crafted HTML pages that manipulate font rendering in ways that cause the memory corruption. Technical details regarding the specific exploitation mechanism are available in the Chromium Issue Tracker Entry.

Detection Methods for CVE-2026-6304

Indicators of Compromise

• Unexpected Chrome renderer crashes followed by unusual system behavior
• Chrome processes spawning child processes outside normal browser operations
• Anomalous memory access patterns in Chrome-related processes
• Network connections originating from Chrome to known malicious infrastructure

Detection Strategies

• Monitor for Chrome version strings indicating unpatched versions prior to 147.0.7727.101
• Implement endpoint detection rules for abnormal Chrome process behavior
• Deploy memory protection technologies that detect use-after-free exploitation attempts
• Utilize browser telemetry to identify crashes in the Graphite component

Monitoring Recommendations

• Enable Chrome's built-in crash reporting and monitor for Graphite-related crashes
• Implement network monitoring for connections from browser processes to suspicious destinations
• Deploy endpoint detection and response (EDR) solutions capable of detecting sandbox escape attempts
• Monitor process creation events for Chrome spawning unexpected child processes

How to Mitigate CVE-2026-6304

Immediate Actions Required

• Update Google Chrome to version 147.0.7727.101 or later immediately
• Enable automatic Chrome updates to ensure timely patch deployment
• Review enterprise browser deployment policies to expedite critical security updates
• Consider temporarily restricting access to untrusted websites until patching is complete

Patch Information

Google has addressed this vulnerability in Chrome version 147.0.7727.101. The fix corrects the memory management issue in the Graphite component to properly handle object lifetimes and prevent use-after-free conditions.

For detailed patch information, refer to the Google Chrome Update Notice.

Organizations using Chromium-based browsers should check with their respective vendors for corresponding security updates.

Workarounds

• Restrict browsing to trusted websites only until the patch can be applied
• Enable Chrome's Site Isolation feature if not already enabled to strengthen process separation
• Consider using browser virtualization or containerization to limit sandbox escape impact
• Implement network-level filtering to block known malicious domains

# Verify Chrome version on Linux/macOS
google-chrome --version

# Force Chrome update check (restart required after update)
# Navigate to: chrome://settings/help

# Enterprise deployment: Push Chrome updates via group policy
# Windows registry key to disable outdated Chrome versions:
# HKLM\Software\Policies\Google\Chrome\RelaunchNotificationPeriod