CVE-2025-4096: Google Chrome Buffer Overflow Vulnerability

CVE-2025-4096 Overview

CVE-2025-4096 is a heap buffer overflow vulnerability in the HTML processing component of Google Chrome. This memory corruption flaw exists in versions prior to 136.0.7103.59 and allows a remote attacker to potentially exploit heap corruption through a crafted HTML page. The vulnerability was assigned a Chromium security severity rating of High, indicating significant risk to affected users.

Heap buffer overflow vulnerabilities in browser HTML rendering engines are particularly dangerous because they can be triggered simply by visiting a malicious website. When the browser's HTML parser processes specially crafted content, it may write data beyond the allocated heap buffer boundaries, potentially corrupting adjacent memory structures and enabling arbitrary code execution within the browser's context.

Critical Impact

Remote attackers can exploit this heap buffer overflow to achieve potential code execution or cause system crashes by delivering malicious HTML content through compromised or attacker-controlled websites.

Affected Products

• Google Chrome versions prior to 136.0.7103.59
• All platforms running vulnerable Chrome versions (Windows, macOS, Linux, ChromeOS)
• Chromium-based browsers that may incorporate the vulnerable code

Discovery Timeline

• 2025-05-05 - CVE-2025-4096 published to NVD
• 2025-05-28 - Last updated in NVD database

Technical Details for CVE-2025-4096

Vulnerability Analysis

This vulnerability is classified as CWE-122 (Heap-based Buffer Overflow), a critical memory safety issue that occurs when a program writes data beyond the boundaries of allocated heap memory. In the context of Google Chrome's HTML processing, this flaw enables attackers to corrupt heap metadata or adjacent data structures, potentially leading to arbitrary code execution.

The vulnerability requires user interaction - specifically, a victim must navigate to a malicious webpage containing the crafted HTML content. The attack is network-based, meaning exploitation can occur remotely without any authentication or special privileges. Once triggered, the heap corruption can compromise the confidentiality, integrity, and availability of the affected system.

Browser-based heap overflows are particularly severe because modern browsers handle sensitive data including authentication tokens, financial information, and personal communications. Successful exploitation could allow attackers to escape the browser sandbox, access user data, or pivot to further attacks on the underlying system.

Root Cause

The root cause of CVE-2025-4096 lies in improper boundary checking within Chrome's HTML parsing and rendering pipeline. When processing certain malformed or specially crafted HTML structures, the vulnerable code fails to properly validate buffer sizes before writing data, resulting in heap memory corruption.

Heap-based buffer overflows typically occur when:

• Dynamic memory allocation does not account for all possible input sizes
• Bounds checking is missing or insufficient during data copying operations
• Integer overflow in size calculations leads to undersized buffer allocation

Attack Vector

The attack vector for this vulnerability is network-based, requiring user interaction through browsing to a malicious webpage. An attacker can exploit this vulnerability by:

1. Creating a malicious website hosting crafted HTML content designed to trigger the heap overflow
2. Distributing links to the malicious page through phishing emails, social media, or compromised legitimate websites
3. When a victim with a vulnerable Chrome version visits the page, the HTML parser processes the malicious content
4. The heap buffer overflow occurs during HTML rendering, corrupting heap memory
5. Depending on heap layout and exploitation technique, the attacker may achieve code execution or cause denial of service

The vulnerability can be exploited through various delivery mechanisms including malvertising campaigns, watering hole attacks on frequently visited sites, or direct phishing attempts targeting specific users or organizations.

Detection Methods for CVE-2025-4096

Indicators of Compromise

• Unexpected Chrome browser crashes or instability when visiting unfamiliar websites
• Chrome crash reports indicating heap corruption in HTML-related components
• Browser process memory anomalies or unexpected memory access patterns
• Suspicious HTML content delivery from untrusted sources with abnormal structure

Detection Strategies

• Monitor Chrome browser version across endpoints to identify unpatched installations running versions below 136.0.7103.59
• Deploy endpoint detection and response (EDR) solutions capable of detecting heap overflow exploitation attempts
• Implement web filtering to block known malicious domains attempting to deliver exploit payloads
• Enable crash dump collection and analysis to identify potential exploitation attempts through crash patterns

Monitoring Recommendations

• Configure centralized logging for browser crash events and correlate with network activity
• Monitor for unusual child process spawning from Chrome that may indicate successful exploitation and sandbox escape
• Track Chrome version deployment status across the organization using software inventory tools
• Implement network traffic analysis to detect suspicious HTML content patterns

How to Mitigate CVE-2025-4096

Immediate Actions Required

• Update Google Chrome to version 136.0.7103.59 or later immediately on all systems
• Enable automatic Chrome updates to ensure timely deployment of future security patches
• Verify Chrome version across all endpoints using enterprise management tools
• Consider temporarily restricting access to untrusted websites until patching is complete

Patch Information

Google has released a fix for this vulnerability in Chrome version 136.0.7103.59. The update was announced in the Stable Channel Update for Desktop. Organizations should prioritize deploying this update across all systems running Google Chrome.

For enterprise environments, administrators can use Google Chrome's enterprise policies to force automatic updates or deploy the patched version through software distribution systems. The Chromium Issue Tracker Entry provides additional technical details about the vulnerability.

Workarounds

• Enable Chrome's Site Isolation feature to limit the impact of potential exploits by isolating websites in separate processes
• Consider using browser security extensions that provide additional protection against malicious web content
• Implement network-level filtering to block access to known malicious domains
• Restrict Chrome extensions and disable unnecessary features to reduce attack surface
• Train users to avoid clicking suspicious links and visiting untrusted websites until the update is deployed

# Verify Chrome version from command line (Linux/macOS)
google-chrome --version
# Or on Windows (PowerShell)
(Get-Item "C:\Program Files\Google\Chrome\Application\chrome.exe").VersionInfo.FileVersion

# Force Chrome update check
# Navigate to: chrome://settings/help
# Or use enterprise deployment tools for managed environments