CVE-2026-11656 Overview
CVE-2026-11656 is a use-after-free vulnerability in the ServiceWorker component of Google Chrome versions prior to 149.0.7827.103. An attacker who convinces a user to install a malicious extension can leverage a crafted Chrome Extension to potentially perform a sandbox escape. Google classified the Chromium security severity as High, and the vulnerability is tracked under CWE-416. The flaw affects Chrome on Windows, macOS, and Linux desktop platforms.
Critical Impact
Successful exploitation enables a sandbox escape from the Chrome renderer, allowing attacker-controlled code to break out of browser isolation boundaries and run with broader privileges on the host system.
Affected Products
- Google Chrome prior to 149.0.7827.103
- Microsoft Windows installations running affected Chrome versions
- Apple macOS and Linux installations running affected Chrome versions
Discovery Timeline
- 2026-06-09 - CVE-2026-11656 published to NVD
- 2026-06-09 - Last updated in NVD database
Technical Details for CVE-2026-11656
Vulnerability Analysis
The vulnerability resides in Chrome's ServiceWorker implementation, a background script mechanism that intercepts network requests and enables offline functionality for web applications. A use-after-free condition occurs when the ServiceWorker component continues to reference memory that has already been deallocated. When an attacker controls allocation patterns through a crafted Chrome extension, the freed memory can be reclaimed with attacker-influenced data. Dereferencing the stale pointer then operates on the controlled content, enabling memory corruption inside the renderer process.
Exploitation requires user interaction in the form of installing a malicious extension. Combined with the Chromium sandbox boundary, this raises attack complexity but does not eliminate risk for users who side-load extensions or install from third-party sources. The Chromium issue is tracked at Chromium Issue 513424000.
Root Cause
The root cause is improper object lifetime management within the ServiceWorker subsystem. An object reference outlives the lifetime of the underlying allocation, leaving a dangling pointer that the extension can groom to point at attacker-controlled data. This pattern aligns with [CWE-416: Use After Free] and is a recurring class of issue in complex browser components that coordinate asynchronous work between renderer, network, and worker threads.
Attack Vector
The attack vector is network-based but gated by social engineering. An attacker publishes or delivers a malicious Chrome extension, persuades a target to install it, and then triggers ServiceWorker code paths from the extension. The extension's elevated privileges relative to ordinary web content make the use-after-free reachable in a way that can lead to a sandbox escape, enabling code execution outside the renderer's restricted environment.
No verified exploit code or public proof-of-concept is available for this issue. The vulnerability mechanism is described in prose because Google has not released technical details beyond the Google Chrome Stable Update advisory.
Detection Methods for CVE-2026-11656
Indicators of Compromise
- Installation of Chrome extensions from outside the official Chrome Web Store, or sudden appearance of unfamiliar extensions in chrome://extensions.
- Chrome renderer or utility process crashes referencing ServiceWorker code paths in crash dump metadata.
- Unexpected child processes spawned by chrome.exe, particularly with command lines that do not match standard renderer or GPU process invocations.
Detection Strategies
- Inventory installed browser extensions across the fleet and compare against an allowlist of approved extension IDs.
- Monitor endpoint telemetry for Chrome process anomalies, including unexpected memory access patterns, unusual module loads, or post-exploitation tooling launched by browser processes.
- Correlate Chrome version data from asset management with the patched build 149.0.7827.103 to identify exposed endpoints.
Monitoring Recommendations
- Enable enterprise reporting through Chrome Browser Cloud Management to surface extension installation events and crash reports.
- Track outbound network connections from Chrome child processes to detect post-sandbox-escape command-and-control activity.
- Alert on writes to autorun locations, scheduled task creation, or credential store access originating from Chrome process trees.
How to Mitigate CVE-2026-11656
Immediate Actions Required
- Update Google Chrome to version 149.0.7827.103 or later on all Windows, macOS, and Linux endpoints.
- Audit installed extensions and remove any that are unsigned, unverified, or installed from outside the Chrome Web Store.
- Enforce extension allowlisting through enterprise policy to block unauthorized extension installation.
Patch Information
Google released the fix in the Stable channel update documented in the Google Chrome Stable Update advisory. Upgrading to Chrome 149.0.7827.103 or later resolves the use-after-free in the ServiceWorker component. Chromium-based browsers downstream of this version should also pick up the fix once they rebase.
Workarounds
- Apply the ExtensionInstallAllowlist and ExtensionInstallBlocklist enterprise policies to restrict which extensions users can install.
- Set ExtensionInstallSources to limit extension installation to trusted update URLs only.
- Where feasible, disable the ServiceWorker capability for untrusted extensions by reviewing extension manifests before approving deployment.
# Configuration example: Chrome enterprise policy to restrict extensions (Windows registry)
reg add "HKLM\Software\Policies\Google\Chrome\ExtensionInstallBlocklist" /v 1 /t REG_SZ /d "*" /f
reg add "HKLM\Software\Policies\Google\Chrome\ExtensionInstallAllowlist" /v 1 /t REG_SZ /d "<approved-extension-id>" /f
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
