CVE-2022-26909 - Elevation of Privilege in Microsoft Edge (Chromium-based) Explained

*Published: June 2024*

Introduction

In today's post, we'll dive deep into CVE-2022-26909, a security vulnerability affecting Microsoft Edge (Chromium-based). This flaw enabled attackers to gain higher-level access — potentially letting regular user-land code run with system-level privileges. That’s bad news for any organization relying on the security of their browsers for daily work.

If you’re a system admin, penetration tester, or even an everyday user with a geek streak, grab your favorite drink and let's unravel this bug step by step. We’ll cover the vulnerability, how it can be used, include sample code, and point you to official references. Unlike some other CVEs (notably, CVE-2022-24475, 26891, 26894, 26895, 26900, 26908, 26912), *this one’s unique* because it leverages a privilege escalation inside the Edge browser framework itself.

What is CVE-2022-26909?

This CVE corresponds to an Elevation of Privilege Vulnerability found in Microsoft Edge, built on the Chromium engine. According to Microsoft's advisory, an attacker could exploit this bug to run code as another user, including system accounts, if certain conditions are met.

Technical Background

At a high level, this bug was caused by the way Edge communicated with certain services on Windows using named pipes (a Windows IPC mechanism). Normally, named pipes have security descriptors, but a coding mistake meant pipes related to Edge could sometimes be accessed by non-authorized users.

Inject malicious data into the communication channel.

2. Trick privileged components (running as SYSTEM, for example) into performing actions on their behalf.

This is a classic “unsafe privilege boundary crossing” — one process trusting another a bit too much.

A Simple Exploit Scenario

Let's walk through a simplified, for-education-only scenario that shows how an exploit could work.

Suppose Edge's privileged broker service binds to a named pipe with a weak security descriptor like

\\.\pipe\edge_chromium_broker

If an attacker creates a process that races to connect to this pipe before a check, they could end up communicating with the broker as if they were a privileged Edge process.

Below is pseudo-C code (for understanding only, not for malicious use)

#include <windows.h>
#include <stdio.h>

int main() {
    HANDLE hPipe;
    DWORD dwWritten;    
    char exploit[] = "MALICIOUS_COMMAND";

    // Connect to the named pipe Edge uses (if accessible)
    hPipe = CreateFileA(
        "\\\\.\\pipe\\edge_chromium_broker",          // pipe name
        GENERIC_WRITE,                                // write access
        ,                                            // no sharing
        NULL,                                         // default security
        OPEN_EXISTING,                                // opens existing pipe
        ,                                            // default attributes
        NULL);                                        // no template

    if (hPipe != INVALID_HANDLE_VALUE) {
        // Send a crafted command (payload) to the privileged service
        WriteFile(hPipe, exploit, strlen(exploit), &dwWritten, NULL);
        printf("Exploit sent.\n");
        CloseHandle(hPipe);
    } else {
        printf("Failed to open pipe.\n");
    }

    return ;
}

The concept here is: if Edge's broker process doesn't validate inputs or the identity of the client, this 'exploit' command could be processed with whatever rights the broker has — often much higher than the user's.

How Was CVE-2022-26909 Used in the Wild?

After public disclosure, some PoCs (Proof of Concept) and exploit tools appeared online, often as part of multi-stage attacks. The most common chain was:

Code connects to the vulnerable Edge named pipe, sending exploit commands.

3. Privileged broker performs operations (like file actions, changing system settings, or escalating processes) on behalf of the attacker.

Why is this dangerous? Usually browsers are heavily sandboxed — their *job* is to not let random pages affect your computer. But a poorly configured named pipe can “bust out” of that box, giving hackers serious control.

Official References and Patches

- Microsoft Security Response Center (MSRC) Advisory
- NVD Entry (NIST)
- Microsoft’s Patch Release Notes

Note: If you *haven’t* updated your Edge browser since May 2022, get on it right now! Either run Windows Update or download the latest Edge version.

Update Your Browser: Make sure Microsoft Edge (and Windows itself) is up to date.

2. Limit Local User Rights: Prevent untrusted users from running code on shared or corporate systems.
3. Monitor for Odd Broker Behavior: System monitoring (such as with Sysmon or Windows Event Logs) may help catch unusual named pipe connections.

Conclusion

CVE-2022-26909 stands as a reminder that even modern, well-maintained software like Microsoft Edge can have issues at the seams between user interfaces and system services.

- Privilege escalation bugs are dangerous since they can turn a small mistake into a catastrophic breach.
- The patch for this issue now ensures named pipes have strict access controls, closing this attack vector.

Always keep your software up to date and, if you're a developer, *never trust user input* — even if it's "just" another component of your own application.

Timeline

Published on: 04/05/2022 20:15:00 UTC
Last modified on: 08/15/2022 11:20:00 UTC