CVE-2026-78985 Overview
CVE-2026-78985 is an incorrect reference resolution vulnerability in the FileSystem component of Google Chrome prior to version 152.0.7977.65. A remote attacker can leverage social engineering to trick a user into visiting a crafted HTML page. Successful exploitation allows arbitrary code execution outside the Chrome sandbox. The flaw is tracked under CWE-706: Use of Incorrectly-Resolved Name or Reference. Chromium rates the internal severity as Medium, while the NVD scoring places it in the higher range due to the sandbox escape impact and scope change.
Critical Impact
Successful exploitation permits arbitrary code execution outside the Chrome sandbox, giving attackers native code execution on the victim host from a single visited web page.
Affected Products
- Google Chrome for Desktop prior to 152.0.7977.65
- Chromium-based browsers incorporating the vulnerable FileSystem code prior to the patched release
- Downstream distributions bundling pre-152 Chrome builds
Discovery Timeline
- 2026-08-25 - CVE-2026-78985 published to the National Vulnerability Database
- 2026-08-27 - CVE record last modified in NVD
Technical Details for CVE-2026-78985
Vulnerability Analysis
The defect lives in Chrome's FileSystem implementation, which resolves references to file objects requested by web content. Under specific conditions, the component resolves a reference to an unintended target [CWE-706]. An attacker who controls a crafted HTML page can manipulate this resolution to reach objects or code paths that should be inaccessible from the renderer's sandboxed context.
Because the flaw enables execution outside the sandbox, exploitation collapses the primary isolation boundary between untrusted web content and the host operating system. The CVSS scope change reflects that impact, and the attack requires only user interaction such as clicking a link or opening a page.
Exploitation is described by the vendor as requiring social engineering, meaning the victim must be directed to attacker-controlled content. No authenticated access or privileged position on the network is required.
Root Cause
The root cause is incorrect reference resolution inside the FileSystem subsystem. When the resolver processes a name or handle supplied through the exposed web API, it maps that input to a different underlying resource than intended. This mismatch enables an attacker to reference internal objects and reach code paths not designed to accept untrusted input, ultimately breaking sandbox containment.
Attack Vector
The attack vector is a crafted HTML page delivered over the network. An attacker hosts malicious content and lures a user to open it, often through phishing emails, malicious advertisements, or compromised sites. Once loaded, the page issues FileSystem API calls that trigger the flawed reference resolution and pivot to code execution outside the renderer sandbox. No verified proof-of-concept exploit has been published for CVE-2026-78985 at the time of writing. Refer to the Chromium Issue Tracker #500038021 for technical details as they become public.
Detection Methods for CVE-2026-78985
Indicators of Compromise
- Chrome renderer or utility processes spawning unexpected child processes such as cmd.exe, powershell.exe, or shell interpreters
- Unexpected file writes originating from the Chrome process tree outside of standard cache and profile directories
- Outbound connections from Chrome child processes to newly observed or low-reputation domains immediately after page navigation
- Chrome installations reporting a version string below 152.0.7977.65 across managed endpoints
Detection Strategies
- Inventory browser versions across the fleet and flag any Chrome build older than 152.0.7977.65
- Alert on anomalous parent-child process chains originating from chrome.exe that lead to native scripting or LOLBins
- Correlate web navigation telemetry with post-navigation process creation to identify drive-by execution patterns
Monitoring Recommendations
- Ingest endpoint process, file, and network telemetry into a centralized data lake for cross-source correlation
- Track Chrome update compliance as a continuous control rather than a point-in-time scan
- Monitor proxy and DNS logs for user visits to newly registered domains, which frequently host social-engineering lures
How to Mitigate CVE-2026-78985
Immediate Actions Required
- Update Google Chrome to version 152.0.7977.65 or later on all managed endpoints
- Restart the browser after the update to ensure the patched binaries are loaded
- Verify update deployment status through enterprise management tooling and remediate hosts still running vulnerable builds
- Communicate phishing awareness guidance to users, since exploitation requires interaction with a crafted page
Patch Information
Google released the fix in the Chrome Stable channel. See the Google Chrome Stable Update announcement for the full advisory and version details. Chromium-based browsers should apply their respective vendor updates once the fix is merged downstream.
Workarounds
- Enforce Chrome auto-update policies through group policy or MDM to prevent version drift
- Restrict access to untrusted external sites via web filtering where feasible until patching completes
- Deploy browser isolation for high-risk user groups such as executives and finance staff
# Verify installed Chrome version on Windows
reg query "HKLM\SOFTWARE\Google\Update\Clients\{8A69D345-D564-463C-AFF1-A69D9E530F96}" /v pv
# Verify installed Chrome version on macOS
defaults read /Applications/Google\ Chrome.app/Contents/Info CFBundleShortVersionString
# 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.
