CVE-2026-5888: Google Chrome WebCodecs Info Disclosure

CVE-2026-5888 Overview

CVE-2026-5888 is an Uninitialized Memory Use vulnerability affecting the WebCodecs component in Google Chrome prior to version 147.0.7727.55. This vulnerability allows a remote attacker to obtain potentially sensitive information from process memory via a crafted HTML page. The vulnerability is classified under CWE-457 (Use of Uninitialized Variable), which occurs when code uses a variable that has not been initialized, leading to unpredictable or unintended results.

Critical Impact

Remote attackers can exploit this vulnerability to extract sensitive information from browser process memory by tricking users into visiting a malicious webpage containing specially crafted HTML and JavaScript code targeting the WebCodecs API.

Affected Products

• Google Chrome prior to version 147.0.7727.55
• Chromium-based browsers using vulnerable WebCodecs implementation
• All desktop platforms running affected Chrome versions (Windows, macOS, Linux)

Discovery Timeline

• 2026-04-08 - CVE CVE-2026-5888 published to NVD
• 2026-04-08 - Last updated in NVD database

Technical Details for CVE-2026-5888

Vulnerability Analysis

This vulnerability exists within the WebCodecs API implementation in Google Chrome. WebCodecs is a browser API that provides low-level access to media encoders and decoders, enabling web applications to process video and audio data with high performance. The vulnerability arises when certain memory regions are accessed before being properly initialized during codec operations.

When processing media data through the WebCodecs API, the browser may read from memory locations that contain residual data from previous operations. This uninitialized memory can contain sensitive information such as portions of previously processed data, internal browser state, or memory from other web origins. An attacker can craft a malicious HTML page that triggers these uninitialized reads and exfiltrates the leaked data.

Root Cause

The root cause is the failure to properly initialize memory buffers before use within the WebCodecs component. Specifically, when allocating memory for codec operations, certain code paths do not zero-initialize or properly set buffer contents before reading from them. This violates safe memory handling practices and allows the contents of previously freed or unallocated memory to be exposed.

The vulnerability falls under CWE-457 (Use of Uninitialized Variable), where variables or memory regions are used before being assigned a deterministic value, leading to information disclosure.

Attack Vector

The attack vector for this vulnerability is network-based, requiring no user authentication. An attacker would need to:

1. Create a malicious webpage that utilizes the WebCodecs API in a manner that triggers the uninitialized memory read
2. Entice a victim to visit the malicious webpage (via phishing, malvertising, or compromised legitimate sites)
3. Execute JavaScript code that reads and exfiltrates the leaked memory contents
4. Process the leaked data to extract sensitive information

The vulnerability can be exploited remotely through a crafted HTML page, making it particularly dangerous in scenarios where users browse untrusted content. The attack does not require any special privileges or user interaction beyond visiting the malicious page.

For detailed technical information about the vulnerability mechanism, refer to the Chromium Issue Tracker Entry and the Google Chrome Update Announcement.

Detection Methods for CVE-2026-5888

Indicators of Compromise

• Unusual JavaScript activity targeting WebCodecs API functions such as VideoDecoder, VideoEncoder, AudioDecoder, or AudioEncoder
• Network traffic containing exfiltrated base64-encoded or binary data following WebCodecs operations
• Browser crash reports or memory access violations related to WebCodecs components
• Suspicious HTML pages with heavy WebCodecs API usage and data exfiltration patterns

Detection Strategies

• Monitor browser extensions and security tools for WebCodecs API abuse patterns
• Implement Content Security Policy (CSP) headers to restrict script execution from untrusted sources
• Deploy endpoint detection solutions capable of identifying browser-based memory disclosure attacks
• Utilize browser isolation technologies to contain potential exploitation attempts

Monitoring Recommendations

• Enable Chrome's built-in Safe Browsing protection to block known malicious sites
• Review web application firewall logs for requests containing WebCodecs-related exploit payloads
• Monitor for Chrome processes exhibiting abnormal memory access patterns
• Track browser version compliance across the enterprise to identify unpatched installations

How to Mitigate CVE-2026-5888

Immediate Actions Required

• Update Google Chrome to version 147.0.7727.55 or later immediately
• Enable automatic browser updates to ensure timely patch deployment
• Audit enterprise environments for outdated Chrome installations using asset management tools
• Consider temporarily disabling WebCodecs API access via Chrome enterprise policies if updates cannot be applied immediately

Patch Information

Google has addressed this vulnerability in Chrome version 147.0.7727.55. The fix ensures proper initialization of memory buffers before use within the WebCodecs component. Organizations should prioritize deploying this update across all managed endpoints.

For official patch details, see the Google Chrome Update Announcement.

Workarounds

• Implement enterprise browser policies to restrict access to untrusted websites
• Consider using browser isolation solutions for high-risk browsing activities
• Deploy network-level filtering to block access to known malicious domains
• Educate users about the risks of visiting untrusted websites and clicking suspicious links

# Chrome Enterprise Policy - Disable WebCodecs (temporary workaround)
# Add to Chrome policy configuration
# Windows: HKLM\SOFTWARE\Policies\Google\Chrome
# macOS: /Library/Managed Preferences/com.google.Chrome.plist
# Linux: /etc/opt/chrome/policies/managed/

# Example policy JSON configuration
{
  "URLBlocklist": ["*://*/webcodecs/*"],
  "ExtensionSettings": {
    "*": {
      "blocked_permissions": ["webcodecs"]
    }
  }
}