CVE-2024-21423: Microsoft Edge Information Disclosure Flaw

CVE-2024-21423 Overview

CVE-2024-21423 is an information disclosure vulnerability in Microsoft Edge (Chromium-based). The flaw is classified under [CWE-693] Protection Mechanism Failure, which allows attackers to bypass a security control that would normally prevent access to sensitive data. Successful exploitation can expose limited confidential information and enable minor integrity changes. Microsoft addressed the issue through the Microsoft Edge update channel and published guidance in the Microsoft Security Update Guide CVE-2024-21423.

Critical Impact
An attacker who exploits this vulnerability can bypass a browser protection mechanism to disclose limited confidential data from Microsoft Edge, though exploitation requires high attack complexity and no authentication.

Affected Products

Microsoft Edge (Chromium-based) — versions prior to the fix documented in the vendor advisory
Windows installations running vulnerable Edge builds
macOS and Linux builds of Microsoft Edge on affected release channels

Discovery Timeline

2024-02-23 - CVE-2024-21423 published to NVD
2026-08-10 - Last updated in NVD database

Technical Details for CVE-2024-21423

Vulnerability Analysis

The vulnerability resides in Microsoft Edge (Chromium-based) and is categorized as an information disclosure issue. Microsoft mapped the weakness to [CWE-693], Protection Mechanism Failure, meaning that a security control designed to protect data operates incorrectly under certain conditions. The result is unintended exposure of limited confidential information rendered or handled by the browser.

Exploitation occurs over the network without authentication or user interaction. However, the attack requires specific preconditions that raise its complexity, such as controlling attacker-hosted content and timing browser behavior appropriately. The impact is bounded to low confidentiality and low integrity loss, with no availability effect according to the CVSS vector.

Microsoft has not released a detailed technical writeup describing the exact code path. Defenders should treat the flaw as a browser-side data exposure that can be triggered when a user visits attacker-controlled or attacker-influenced web content.

Root Cause

The root cause is a failure of a browser protection mechanism ([CWE-693]) that should isolate or restrict access to certain data. Because Microsoft has not published component-level details, the specific subsystem is not publicly documented. Refer to the Microsoft Security Update Guide CVE-2024-21423 for vendor guidance.

Attack Vector

An attacker delivers crafted web content to a targeted user of Microsoft Edge. When the browser processes the content, the protection mechanism fails to enforce its expected boundary, leaking limited information to the attacker-controlled context. No credentials are required, and no direct user interaction beyond normal browsing is needed.

No public proof-of-concept, exploit code, or CISA KEV listing exists for this CVE at the time of writing. The EPSS score reported by FIRST indicates a low probability of exploitation in the near term.

Detection Methods for CVE-2024-21423

Indicators of Compromise

No public indicators of compromise have been published for CVE-2024-21423.
Investigate anomalous outbound requests from Microsoft Edge processes (msedge.exe) to untrusted domains shortly after visits to unfamiliar sites.
Correlate browser telemetry with unexpected data flows from user endpoints to external hosts.

Detection Strategies

Inventory Microsoft Edge versions across the environment and flag endpoints running builds older than the patched release listed in the vendor advisory.
Monitor endpoint telemetry for browser child processes performing unusual file, memory, or network operations following web navigation events.
Enable browser security logging and forward events to a centralized analytics platform for correlation with threat intelligence.

Monitoring Recommendations

Track Microsoft Edge update compliance through configuration management or Microsoft Intune reporting.
Alert on execution of msedge.exe with abnormal command-line arguments or extension loads from non-approved sources.
Review web proxy logs for repeated user visits to newly registered or low-reputation domains that may host exploit content.

How to Mitigate CVE-2024-21423

Immediate Actions Required

Update Microsoft Edge to the patched version identified in the Microsoft Security Update Guide CVE-2024-21423.
Verify that Microsoft Edge auto-update is enabled across managed endpoints and confirm the current installed version via edge://settings/help.
Prioritize patching for high-value users such as executives, developers, and administrators who may be targeted with crafted web content.

Patch Information

Microsoft released a corrective update through the Microsoft Edge (Chromium-based) channel. Consult the Microsoft Security Update Guide CVE-2024-21423 for the specific fixed build number and rollout schedule for each supported platform. Enterprise administrators should validate patch deployment status through Microsoft Endpoint Configuration Manager or Microsoft Intune.

Workarounds

No official workaround has been published by Microsoft; applying the vendor update is the recommended remediation.
Restrict browsing to trusted sites through web proxy filtering or SmartScreen policies to reduce exposure until patching completes.
Enforce least-privilege browser configurations, disable unnecessary extensions, and prevent installation of untrusted add-ons via group policy.

bash

# Configuration example: verify Microsoft Edge version on Windows endpoints
reg query "HKLM\SOFTWARE\Microsoft\Edge\BLBeacon" /v version

# Force an Edge update check via Microsoft Edge Update service
"C:\Program Files (x86)\Microsoft\EdgeUpdate\MicrosoftEdgeUpdate.exe" /ua /installsource scheduler