CVE-2026-79263: Google Chrome Extensions RCE Vulnerability

CVE-2026-79263 Overview

CVE-2026-79263 is a race condition vulnerability in the Extensions component of Google Chrome prior to version 152.0.7977.65. A remote attacker can exploit the flaw through crafted network traffic to execute arbitrary code inside the Chrome sandbox. The issue is classified as [CWE-367]: Time-of-check Time-of-use (TOCTOU) race condition. Chromium security rated the underlying issue as Low severity, while NVD scored it in the High range due to broad impact potential.

Critical Impact
Successful exploitation allows remote arbitrary code execution within the Chrome sandbox process, enabling attackers to run attacker-controlled code on affected client systems without user credentials.

Affected Products

Google Chrome Desktop versions prior to 152.0.7977.65
Chromium-based browsers that ship the vulnerable Extensions component
Downstream distributions embedding pre-patched Chromium builds

Discovery Timeline

2026-08-25 - CVE-2026-79263 published to the National Vulnerability Database
2026-08-27 - Last updated in NVD database

Technical Details for CVE-2026-79263

Vulnerability Analysis

The vulnerability resides in the Extensions subsystem of Google Chrome. It is a race condition, categorized under [CWE-367] as a Time-of-check Time-of-use (TOCTOU) weakness. In this class of flaw, the state of a resource changes between the moment it is validated and the moment it is used. An attacker who wins the race can substitute attacker-controlled data or objects after security checks pass, causing the browser to operate on unvalidated state.

The advisory indicates the flaw is reachable via crafted network traffic. This means an attacker can trigger the vulnerable code path by serving malicious content that a Chrome extension or the extension platform processes. Successful exploitation results in arbitrary code execution inside the Chrome sandbox process rather than direct host compromise.

Root Cause

The root cause is concurrent access to shared state within the Extensions component without adequate synchronization. Chromium engineers addressed the issue in the fix landed under Chromium Issue #497256260 and released in the stable channel update 152.0.7977.65.

Attack Vector

Exploitation requires no authentication and no user interaction beyond loading attacker-controlled content, but attack complexity is high because the attacker must win a timing race. A remote attacker delivers crafted network traffic that the Extensions subsystem processes concurrently with a security-relevant check, allowing malicious input to replace validated data before use. For technical details, refer to the Google Chrome Stable Update advisory and the linked Chromium issue tracker entry.

Detection Methods for CVE-2026-79263

Indicators of Compromise

Chrome renderer or extension utility processes spawning unexpected child processes such as command shells or script interpreters.
Outbound connections from Chrome processes to unfamiliar hosts immediately following extension activity.
Unexpected modifications to files under the Chrome user data directory, particularly under Extensions and Local Extension Settings.

Detection Strategies

Inventory Chrome versions across the fleet and flag any endpoint running a build earlier than 152.0.7977.65.
Alert on anomalous parent-child process relationships where chrome.exe or its helpers launch scripting engines or LOLBins.
Correlate browser telemetry with network telemetry to identify sessions where extension traffic precedes suspicious process activity.

Monitoring Recommendations

Enable enterprise browser telemetry and forward events to a centralized analytics platform for retention and correlation.
Monitor extension installation and update events across managed Chrome deployments through Chrome Browser Cloud Management.
Track EDR alerts for in-memory code execution originating from renderer and extension processes.

How to Mitigate CVE-2026-79263

Immediate Actions Required

Update Google Chrome to version 152.0.7977.65 or later on all managed endpoints.
Force-restart Chrome after deployment so the patched binary is loaded into memory.
Audit installed extensions and remove any that are unused, unverified, or sourced outside the Chrome Web Store.

Patch Information

Google released the fix in the Chrome stable channel version 152.0.7977.65. Refer to the Google Chrome Stable Update announcement for the full advisory and to Chromium Issue #497256260 for the associated bug tracker entry.

Workarounds

Use enterprise policy to restrict extension installation to an allowlist while patch deployment is in progress.
Deploy the update through managed software distribution to reduce the window of exposure.
Segment high-risk users behind network egress controls that limit reachability of untrusted origins.

bash

# Example: enforce Chrome extension allowlist via enterprise policy on Linux
# /etc/opt/chrome/policies/managed/extension_policy.json
{
  "ExtensionInstallBlocklist": ["*"],
  "ExtensionInstallAllowlist": [
    "<approved-extension-id-1>",
    "<approved-extension-id-2>"
  ],
  "ExtensionSettings": {
    "*": {
      "installation_mode": "blocked"
    }
  }
}