CVE-2024-3840: Google Chrome Auth Bypass Vulnerability

CVE-2024-3840 Overview

CVE-2024-3840 is an insufficient policy enforcement vulnerability in the Site Isolation component of Google Chrome before version 124.0.6367.60. A remote attacker can bypass navigation restrictions by serving a crafted HTML page, undermining the integrity boundaries that Site Isolation is designed to enforce between origins.

Google classified the issue as Medium severity in its Chromium advisory, while NVD assigned a higher score driven by network exploitability and integrity impact. The flaw is tracked under [CWE-285: Improper Authorization] and affects Google Chrome on all desktop platforms, as well as Chromium-based packages distributed by Fedora.

Critical Impact
Remote attackers can bypass Chrome's Site Isolation navigation restrictions through a crafted HTML page, weakening browser-enforced origin boundaries used to contain cross-site attacks.

Affected Products

Google Chrome prior to 124.0.6367.60
Fedora 38, 39, and 40 (chromium package)
Chromium-based browsers sharing the upstream Site Isolation implementation

Discovery Timeline

2024-04-16 - Google releases Chrome 124.0.6367.60 to the Stable channel for desktop, addressing the issue
2024-04-17 - CVE-2024-3840 published to the National Vulnerability Database
2024-12-19 - Last updated in NVD database

Technical Details for CVE-2024-3840

Vulnerability Analysis

The vulnerability resides in Chrome's Site Isolation feature, which segregates content from different sites into distinct renderer processes. Site Isolation enforces navigation policies so that a compromised or malicious page cannot drive the browser into states that violate origin boundaries.

Insufficient policy enforcement in the navigation logic allows a crafted HTML page to bypass these restrictions. An attacker can manipulate navigation flows in ways the policy layer should have blocked, weakening cross-origin protections that downstream defenses depend on.

The issue is referenced in the upstream Chromium Issue Tracker Entry and fixed in the Stable channel update announced in the Chrome Desktop Update Announcement. Exploitation requires no privileges and no user interaction beyond loading attacker-controlled content.

Root Cause

The root cause is improper authorization [CWE-285] within Site Isolation navigation policy checks. The browser fails to fully validate certain navigation transitions against the expected isolation boundaries, allowing attacker-crafted markup to direct the browser into states that should be disallowed.

Attack Vector

Exploitation occurs over the network. An attacker hosts a malicious HTML page and lures a victim using a vulnerable Chrome build to visit it, or injects the content via a compromised site or malvertising. The crafted page triggers navigation sequences that evade Site Isolation enforcement, enabling actions that violate same-site assumptions used by web applications and other browser features.

No public proof-of-concept or exploit module has been published for this CVE, and it is not listed in the CISA Known Exploited Vulnerabilities catalog. Refer to the Chromium issue tracker for technical details once Google opens access to the bug.

Detection Methods for CVE-2024-3840

Indicators of Compromise

Chrome browser builds reporting versions earlier than 124.0.6367.60 in endpoint inventory or chrome://version telemetry
Outbound connections from Chrome to newly registered or low-reputation domains immediately followed by anomalous cross-site navigation chains
Browser crash or renderer process anomalies coinciding with visits to untrusted HTML content

Detection Strategies

Inventory installed Chrome and Chromium versions across managed endpoints and flag hosts below 124.0.6367.60
Correlate web proxy logs with endpoint browsing telemetry to identify users loading suspicious HTML pages prior to anomalous renderer activity
Monitor for Fedora chromium package versions that predate the patched builds referenced in the Fedora package announcements

Monitoring Recommendations

Ingest browser version data and web access logs into a centralized analytics platform to identify unpatched clients and risky navigation patterns
Track Chrome auto-update health using management tools such as Chrome Browser Cloud Management to confirm enterprise-wide patch coverage
Alert on policy-managed Chrome instances where auto-update has been disabled or pinned to versions below 124.0.6367.60

How to Mitigate CVE-2024-3840

Immediate Actions Required

Update Google Chrome to version 124.0.6367.60 or later on Windows, macOS, and Linux endpoints
Apply the Fedora chromium security updates referenced in the Fedora package announcements for Fedora 38, 39, and 40
Restart Chrome on all endpoints after update to ensure the patched binary is loaded
Verify enterprise update policies are not blocking or delaying Stable channel updates

Patch Information

Google addressed the vulnerability in Chrome Stable channel release 124.0.6367.60, announced in the Chrome Desktop Update Announcement. Fedora published corresponding chromium package updates for Fedora 38, 39, and 40 via the Fedora project mailing list. Chromium-based browsers such as Microsoft Edge, Brave, Opera, and Vivaldi should be updated to releases that incorporate the same upstream fix.

Workarounds

No vendor-supplied workaround exists; applying the patched Chrome build is required
Restrict browsing to trusted sites using enterprise web filtering until all endpoints are updated
Use group policy or MDM to enforce minimum Chrome version requirements and block launch of outdated builds where supported

bash

# Verify Chrome version on Linux endpoints
google-chrome --version

# Upgrade Chromium on Fedora
sudo dnf upgrade --refresh chromium

# Windows: confirm version via registry
reg query "HKLM\SOFTWARE\Google\Update\Clients\{8A69D345-D564-463C-AFF1-A69D9E530F96}" /v pv