CVE-2026-5873: Google Chrome V8 RCE Vulnerability

CVE-2026-5873 Overview

An out-of-bounds read and write vulnerability exists in the V8 JavaScript engine in Google Chrome prior to version 147.0.7727.55. This memory corruption flaw allows a remote attacker to execute arbitrary code inside the Chrome sandbox by convincing a victim to visit a maliciously crafted HTML page. The vulnerability has been classified with High severity by Chromium security.

Critical Impact

Remote code execution within sandbox via crafted web page - attackers can exploit this vulnerability through drive-by downloads without requiring user interaction beyond visiting a malicious website.

Affected Products

• Google Chrome prior to version 147.0.7727.55
• Chromium-based browsers using vulnerable V8 versions
• Applications embedding vulnerable V8 engine versions

Discovery Timeline

• 2026-04-08 - CVE-2026-5873 published to NVD
• 2026-04-08 - Last updated in NVD database

Technical Details for CVE-2026-5873

Vulnerability Analysis

This vulnerability affects the V8 JavaScript engine, which is the core component responsible for executing JavaScript code in Google Chrome and Chromium-based browsers. The flaw enables both out-of-bounds read and write operations, a particularly dangerous combination that provides attackers with the capability to both leak memory contents and corrupt memory structures.

V8 processes JavaScript code through multiple optimization pipelines, including the TurboFan optimizing compiler. Memory corruption vulnerabilities in V8 typically arise from incorrect bounds checking, type confusion during optimization, or improper handling of array operations. The dual nature of this vulnerability (read and write primitives) significantly increases its exploitability, as attackers can use the read primitive to bypass security mitigations like ASLR before leveraging the write primitive for code execution.

While execution occurs within Chrome's sandbox, a successful exploit could be chained with a sandbox escape vulnerability to achieve full system compromise.

Root Cause

The vulnerability stems from improper bounds validation in V8's memory access operations. When processing specially crafted JavaScript, the engine fails to properly validate array indices or object property accesses, leading to memory operations outside the intended buffer boundaries. This type of flaw commonly occurs in JIT-compiled code where aggressive optimizations may incorrectly remove bounds checks that are still necessary for security.

Attack Vector

The attack requires the victim to navigate to a malicious web page controlled by the attacker. The crafted HTML page contains JavaScript code specifically designed to trigger the out-of-bounds memory access in the V8 engine.

The exploitation sequence involves:

1. The attacker hosts a malicious webpage containing crafted JavaScript
2. The victim visits the page, either directly or through phishing/redirect chains
3. V8 processes the malicious JavaScript, triggering the out-of-bounds condition
4. The attacker achieves arbitrary read/write primitives within the renderer process
5. Code execution occurs within the Chrome sandbox

Since this vulnerability requires no special permissions or user interaction beyond visiting a webpage, it represents a significant threat for drive-by attacks. Additional vulnerability chaining would be required to escape the sandbox for full system access.

Detection Methods for CVE-2026-5873

Indicators of Compromise

• Unusual Chrome renderer process crashes or unexpected restarts
• Browser tabs consuming excessive memory before crashing
• Suspicious JavaScript execution patterns in browser logs
• Anomalous network traffic to unknown domains immediately following webpage visits

Detection Strategies

• Monitor for Chrome renderer process crashes that may indicate exploitation attempts
• Implement network-level detection for known malicious domains hosting exploit code
• Deploy browser extension policies to block JavaScript execution on untrusted sites
• Enable Chrome's Enhanced Safe Browsing for improved protection against malicious pages

Monitoring Recommendations

• Enable Chrome crash reporting to identify potential exploitation patterns
• Monitor endpoint detection systems for post-exploitation behavior following browser activity
• Review web proxy logs for access to suspicious or newly registered domains
• Implement DNS monitoring for connections to known command and control infrastructure

How to Mitigate CVE-2026-5873

Immediate Actions Required

• Update Google Chrome to version 147.0.7727.55 or later immediately
• Enable automatic Chrome updates to receive future security patches promptly
• Consider temporarily using alternative browsers for high-risk browsing activities until patching is complete
• Implement network-level blocking of known malicious domains

Patch Information

Google has released Chrome version 147.0.7727.55 which addresses this vulnerability. Organizations should prioritize updating all Chrome installations across their environment. For detailed information about the update, refer to the Google Chrome Releases Blog. The vulnerability is tracked in the Chromium Issue Tracker.

Chrome typically auto-updates, but administrators should verify that updates are successfully applied across managed endpoints. Enterprise environments using Chrome management policies should push the update immediately.

Workarounds

• Disable JavaScript execution globally or for untrusted sites until patching is possible
• Use browser isolation technologies to contain potential exploitation
• Implement strict Content Security Policies (CSP) on internal applications
• Consider enabling Site Isolation if not already active

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

# Force Chrome update check (command line launch with update flag)
google-chrome --check-for-update-interval=0

# Windows: Check Chrome version via PowerShell
(Get-ItemProperty 'HKLM:\SOFTWARE\Google\Chrome\BLBeacon' -Name 'version').version