CVE-2026-78951 Overview
CVE-2026-78951 is a use-after-free vulnerability in the ServiceWorker component of Google Chrome prior to version 152.0.7977.65. A remote attacker can execute arbitrary code outside the browser sandbox by convincing a user to visit a crafted HTML page. The flaw is tracked under CWE-416: Use After Free and affects Chrome across desktop platforms. Google's Chromium team rated the underlying issue as Medium severity, while NVD scored the CVE as Critical due to the sandbox escape and code execution impact.
Critical Impact
Successful exploitation grants arbitrary code execution outside the Chrome sandbox, giving attackers a foothold on the underlying operating system.
Affected Products
- Google Chrome for Desktop prior to 152.0.7977.65
- Chromium-based browsers sharing the vulnerable ServiceWorker code path
- Embedded applications using vulnerable Chromium builds
Discovery Timeline
- 2026-08-25 - CVE-2026-78951 published to NVD
- 2026-08-27 - Last updated in NVD database
Technical Details for CVE-2026-78951
Vulnerability Analysis
The vulnerability resides in Chrome's ServiceWorker implementation. ServiceWorkers are background scripts that intercept network requests, manage caches, and enable offline functionality for web applications. A use-after-free condition occurs when the browser process references a ServiceWorker object after its backing memory has been released. An attacker who reclaims the freed memory with controlled data can hijack execution flow inside a privileged browser process. Because ServiceWorker logic executes outside the renderer sandbox for portions of its lifecycle, corruption in this component enables a sandbox escape rather than remaining confined to a single tab.
Root Cause
The root cause is improper object lifetime management within the ServiceWorker subsystem. A dangling pointer persists after the associated object has been deallocated, and subsequent operations dereference the stale reference. This class of defect is tracked as CWE-416 and is a recurring pattern in complex, event-driven browser components.
Attack Vector
Exploitation is network-based and requires user interaction. A victim visits an attacker-controlled or compromised page that registers or interacts with a malicious ServiceWorker. The crafted HTML and JavaScript trigger the specific sequence needed to free and reuse the target object. Because the scope changes from renderer to browser process, the impact crosses a security boundary. Public exploit code is not currently listed for this CVE, and it does not appear on the CISA Known Exploited Vulnerabilities catalog.
No verified proof-of-concept code has been published. Technical details are tracked in the Chromium Issue Tracker #522957054 and the Google Chrome Desktop Update advisory.
Detection Methods for CVE-2026-78951
Indicators of Compromise
- Chrome renderer or browser process crashes with heap corruption signatures shortly after visiting a new site
- Unexpected child processes spawned by chrome.exe following ServiceWorker registration events
- Outbound connections from Chrome to previously unseen domains hosting suspicious service-worker.js payloads
Detection Strategies
- Inventory installed Chrome versions across the fleet and flag any build below 152.0.7977.65
- Monitor endpoint telemetry for anomalous behavior originating from Chrome processes, including code execution outside expected sandbox constraints
- Correlate browser crash reports with web proxy logs to identify pages that consistently precede failures
Monitoring Recommendations
- Enable EDR behavioral rules covering browser exploitation techniques such as process hollowing and unexpected memory allocations in Chrome
- Forward Chrome crash dumps and browser event logs into a centralized data lake for retrospective hunting
- Track ServiceWorker registration events from managed browsers using enterprise browser telemetry where available
How to Mitigate CVE-2026-78951
Immediate Actions Required
- Update Google Chrome to version 152.0.7977.65 or later on all managed endpoints
- Restart the browser after patching to ensure the vulnerable code is no longer resident in memory
- Push the update to Chromium-based derivatives once their vendors ship the corresponding fix
Patch Information
Google addressed the issue in the Stable channel update documented in the Google Chrome Desktop Update advisory. Enterprise administrators should validate that automatic updates are functioning and use group policy to enforce the minimum required version. Reference the Chromium Issue Tracker #522957054 for the underlying commit metadata once made public.
Workarounds
- Restrict browsing to trusted sites via enterprise policy until patching completes
- Disable ServiceWorker functionality for high-risk user groups using Chrome enterprise policies where feasible
- Deploy web filtering to block newly registered or low-reputation domains that could host exploit pages
# Verify installed Chrome version on Windows endpoints
reg query "HKLM\Software\Google\Update\Clients\{8A69D345-D564-463C-AFF1-A69D9E530F96}" /v pv
# Verify installed Chrome version on macOS
/Applications/Google\ Chrome.app/Contents/MacOS/Google\ Chrome --version
# Verify installed Chrome version on Linux
google-chrome --version
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
