CVE-2026-6311: Google Chrome RCE Vulnerability

CVE-2026-6311 Overview

CVE-2026-6311 is a high-severity uninitialized memory use vulnerability in the Accessibility component of Google Chrome on Windows. This flaw allows a remote attacker who has already compromised the renderer process to potentially escape the browser sandbox through a crafted HTML page. The vulnerability affects Google Chrome versions prior to 147.0.7727.101 and has been classified with Chromium security severity as High.

Critical Impact

Successful exploitation enables sandbox escape from a compromised renderer process, potentially allowing attackers to execute arbitrary code outside the browser's security boundary with elevated privileges on the underlying Windows system.

Affected Products

• Google Chrome on Windows prior to version 147.0.7727.101
• Chromium-based browsers on Windows using affected Accessibility code

Discovery Timeline

• 2026-04-15 - CVE-2026-6311 published to NVD
• 2026-04-15 - Last updated in NVD database

Technical Details for CVE-2026-6311

Vulnerability Analysis

This vulnerability stems from the use of uninitialized memory (CWE-457) within Chrome's Accessibility subsystem on Windows. The Accessibility component provides interfaces for assistive technologies such as screen readers to interact with browser content. When specific accessibility features are invoked through a crafted HTML page, the browser may reference memory that has not been properly initialized.

In a multi-process browser architecture like Chrome, the renderer process handles untrusted web content and is isolated within a sandbox. However, uninitialized memory conditions can expose sensitive data or create exploitable states that allow an attacker who has already compromised the renderer to escalate their access. By carefully crafting the HTML page and timing the memory access, an attacker could leverage the uninitialized values to manipulate control flow or data structures, ultimately achieving sandbox escape.

The attack requires user interaction (visiting a malicious page) and the attacker must first compromise the renderer process, making this a chained attack scenario. Nevertheless, the potential for sandbox escape makes this a critical concern for enterprise environments.

Root Cause

The root cause is the use of uninitialized memory in the Accessibility component. Specifically, certain code paths in the Accessibility subsystem fail to properly initialize memory before use. When the renderer process interacts with Windows accessibility APIs through Inter-Process Communication (IPC), uninitialized data structures can be passed to the browser process, creating an exploitable condition.

This type of vulnerability typically occurs when:

• Memory is allocated but not zero-initialized before use
• Conditional paths skip initialization routines
• Object fields are accessed before constructors complete

Attack Vector

The attack is network-based and requires user interaction. An attacker would need to:

1. Host or inject a malicious HTML page on a website the victim visits
2. First achieve renderer process compromise through a separate vulnerability or existing foothold
3. Trigger the accessibility code path with crafted content
4. Exploit the uninitialized memory condition to escape the sandbox
5. Execute code with the privileges of the browser process outside the sandbox

The vulnerability mechanism involves crafted HTML content that exercises specific accessibility features in a manner that triggers uninitialized memory reads or writes. For detailed technical analysis, refer to the Chromium Issue Tracker once the issue is made public.

Detection Methods for CVE-2026-6311

Indicators of Compromise

• Unusual Chrome browser process behavior, including unexpected child processes spawning outside the sandbox
• Accessibility-related API calls from the browser process with anomalous patterns
• Evidence of renderer process attempting to access resources outside its sandbox boundary
• Suspicious network connections originating from browser processes following accessibility feature usage

Detection Strategies

• Monitor for Chrome processes running versions prior to 147.0.7727.101 across the enterprise
• Implement endpoint detection rules for sandbox escape patterns, including unexpected privilege escalation from browser processes
• Deploy memory integrity monitoring tools to detect uninitialized memory access patterns
• Utilize SentinelOne's behavioral AI to identify anomalous browser process behavior indicative of exploitation

Monitoring Recommendations

• Enable Chrome enterprise logging and forward browser crash reports to SIEM for analysis
• Monitor Windows Event Logs for suspicious accessibility API interactions
• Track Chrome version deployment across endpoints to identify unpatched systems
• Implement network segmentation alerts for browser processes initiating unusual outbound connections

How to Mitigate CVE-2026-6311

Immediate Actions Required

• Update Google Chrome to version 147.0.7727.101 or later immediately
• Enable automatic Chrome updates across all managed endpoints
• Restrict browsing to trusted websites until patching is complete in high-security environments
• Consider temporarily disabling non-essential accessibility features on sensitive systems if immediate patching is not feasible

Patch Information

Google has released Chrome version 147.0.7727.101 which addresses this vulnerability. The patch properly initializes memory in the Accessibility component before use, eliminating the uninitialized memory condition.

For detailed patch information, see the Google Chrome Stable Update announcement.

Organizations should prioritize this update given the potential for sandbox escape. Chrome's built-in update mechanism will automatically apply this fix; however, enterprise deployments may require manual intervention through group policy or endpoint management solutions.

Workarounds

• Deploy Chrome Enterprise policies to restrict access to untrusted websites
• Use application allowlisting to prevent execution of unauthorized code even if sandbox escape occurs
• Enable Site Isolation and Strict Site Isolation policies to add additional process boundaries
• Consider using alternative browsers on critical systems until Chrome is updated

# Chrome Enterprise Policy Configuration via Registry
# Force Chrome updates and enable strict site isolation

reg add "HKLM\SOFTWARE\Policies\Google\Update" /v "AutoUpdateCheckPeriodMinutes" /t REG_DWORD /d 60 /f
reg add "HKLM\SOFTWARE\Policies\Google\Chrome" /v "SitePerProcess" /t REG_DWORD /d 1 /f
reg add "HKLM\SOFTWARE\Policies\Google\Chrome" /v "IsolateOrigins" /t REG_SZ /d "*" /f