CVE-2026-3915: Google Chrome WebML Buffer Overflow Flaw

CVE-2026-3915 Overview

A heap buffer overflow vulnerability exists in the WebML component of Google Chrome versions prior to 146.0.7680.71. This memory corruption flaw allows a remote attacker to perform an out-of-bounds memory read by luring a user to visit a specially crafted HTML page. The vulnerability is classified as CWE-122 (Heap-based Buffer Overflow) and represents a significant security risk in the browser's machine learning processing capabilities.

Critical Impact

Remote attackers can exploit this heap buffer overflow to read sensitive memory contents, potentially enabling information disclosure or further exploitation chains that could lead to arbitrary code execution within the browser's sandbox.

Affected Products

• Google Chrome versions prior to 146.0.7680.71
• Chromium-based browsers using vulnerable WebML implementation
• Desktop platforms running affected Chrome versions (Windows, macOS, Linux)

Discovery Timeline

• 2026-03-11 - CVE CVE-2026-3915 published to NVD
• 2026-03-12 - Last updated in NVD database

Technical Details for CVE-2026-3915

Vulnerability Analysis

This heap buffer overflow vulnerability resides in Google Chrome's WebML (Web Machine Learning) component, which provides APIs for hardware-accelerated machine learning operations within the browser. The flaw occurs when the WebML implementation processes maliciously crafted input data, leading to improper memory boundary validation during heap buffer operations.

The vulnerability requires user interaction—specifically, the victim must navigate to an attacker-controlled webpage containing the malicious HTML payload. Once triggered, the overflow condition allows reading memory beyond the allocated heap buffer boundaries, potentially exposing sensitive data from the browser's memory space.

Root Cause

The root cause is improper bounds checking in the WebML component's memory handling routines. When processing certain machine learning model inputs or tensor operations, the code fails to properly validate input sizes against allocated buffer capacities. This allows an attacker to craft input that exceeds expected boundaries, causing the heap buffer to overflow during read operations.

The CWE-122 classification indicates this is specifically a heap-based buffer overflow, where dynamically allocated memory on the heap is overread due to insufficient validation of array indices or pointer arithmetic.

Attack Vector

The attack is network-based and requires the attacker to craft a malicious HTML page that leverages the WebML API to trigger the vulnerable code path. The exploitation flow involves:

1. Attacker creates a webpage with malicious JavaScript utilizing the WebML API
2. Victim visits the attacker-controlled page or is redirected via phishing
3. The browser's WebML component processes the crafted payload
4. Buffer overflow occurs, allowing out-of-bounds memory read
5. Sensitive data from adjacent heap memory may be disclosed to the attacker

The attack does not require prior authentication or special privileges, but does require user interaction to navigate to the malicious page. For detailed technical information, refer to the Chromium Issue Tracker Entry.

Detection Methods for CVE-2026-3915

Indicators of Compromise

• Unusual WebML API calls with abnormal tensor dimensions or data sizes in JavaScript execution
• Browser crash reports indicating heap corruption in WebML-related modules
• Memory access violations or segmentation faults in Chrome's renderer process
• Unexpected network connections to suspicious domains combined with high JavaScript activity

Detection Strategies

• Monitor for Chrome crash dumps containing WebML component stack traces
• Implement browser extension or endpoint detection rules to flag suspicious WebML API usage patterns
• Deploy network-based detection for known malicious page patterns targeting this vulnerability
• Utilize memory protection tools to detect out-of-bounds read attempts in browser processes

Monitoring Recommendations

• Enable Chrome's built-in crash reporting and monitor for WebML-related crashes
• Deploy endpoint detection and response (EDR) solutions capable of monitoring browser memory operations
• Implement web proxy logging to track navigation to potentially malicious domains
• Configure SIEM rules to correlate browser crashes with recent web navigation activity

How to Mitigate CVE-2026-3915

Immediate Actions Required

• Update Google Chrome to version 146.0.7680.71 or later immediately
• Enable automatic updates in Chrome to ensure timely security patches
• Consider restricting access to untrusted websites until patching is complete
• Review browser policies to limit JavaScript execution on untrusted domains

Patch Information

Google has released Chrome version 146.0.7680.71 which addresses this vulnerability. The update should be applied as soon as possible to all affected systems. For detailed release information, see the Google Chrome Update Announcement.

To verify your Chrome version:

1. Open Chrome and navigate to chrome://settings/help
2. Confirm version is 146.0.7680.71 or higher
3. If not updated, Chrome will automatically download and install the update

Workarounds

• Disable JavaScript execution on untrusted sites using browser settings or extensions
• Utilize browser isolation technologies to contain potential exploitation
• Configure enterprise policies to restrict WebML API access if not business-critical
• Deploy network-level filtering to block access to known malicious domains

# Chrome enterprise policy to force updates (Windows)
reg add "HKLM\SOFTWARE\Policies\Google\Update" /v "Update{8A69D345-D564-463C-AFF1-A69D9E530F96}" /t REG_DWORD /d 1 /f

# Verify Chrome version via command line (macOS/Linux)
google-chrome --version
# Expected output: Google Chrome 146.0.7680.71 or higher