CVE-2026-21138: Smart Switch Auth Bypass Vulnerability

CVE-2026-21138 Overview

CVE-2026-21138 affects Samsung Smart Switch prior to version 3.7.73. The vulnerability stems from insufficient verification of data authenticity during application handling. A physical attacker with access to the device can leverage this flaw to install arbitrary applications without proper validation.

The issue requires physical access to the target device, which limits remote exploitation scenarios. However, successful exploitation enables an attacker to introduce unauthorized software onto a victim's device, bypassing standard installation integrity checks.

Critical Impact
A physical attacker can install arbitrary applications on a device running a vulnerable Samsung Smart Switch client, compromising system integrity and introducing untrusted code.

Affected Products

Samsung Smart Switch versions prior to 3.7.73
Mobile devices with the vulnerable Smart Switch client installed
Both source and destination devices during Smart Switch transfer operations

Discovery Timeline

2026-10-12 - CVE-2026-21138 published to NVD
2026-10-15 - Last updated in NVD database

Technical Details for CVE-2026-21138

Vulnerability Analysis

Samsung Smart Switch facilitates data migration between mobile devices, including the transfer of applications and user content. The vulnerability resides in the client's handling of application data authenticity checks before installation.

Because Smart Switch does not sufficiently verify the authenticity of application data before installation, an attacker with physical access can supply crafted application payloads. The client installs these payloads as if they were legitimate, allowing arbitrary application execution on the device.

This class of weakness falls under insufficient verification of data authenticity (CWE-345). It enables attackers to bypass trust assumptions built into Android's package installation model when Smart Switch brokers the installation flow.

Root Cause

The root cause is the absence of adequate signature or integrity validation on application data processed by Smart Switch. The client trusts incoming application payloads during the transfer workflow without enforcing authenticity controls that would reject tampered or attacker-supplied packages.

Attack Vector

Exploitation requires physical access to the target device (AV:P). An attacker initiates a Smart Switch transfer or interacts with the Smart Switch client directly to feed a malicious application payload. No privileges or user interaction beyond the physical access are required to complete the installation.

The vulnerability manifests during application handling by the Smart Switch client. Refer to the Samsung Mobile Security Advisory for vendor technical details.

Detection Methods for CVE-2026-21138

Indicators of Compromise

Unexpected applications appearing on a device following a Smart Switch transfer operation
Installation of applications originating from unverified sources through the Smart Switch workflow
Smart Switch client versions prior to 3.7.73 present on managed mobile devices

Detection Strategies

Inventory mobile endpoints to identify Smart Switch installations older than version 3.7.73
Monitor mobile device management (MDM) application inventories for unauthorized package installations after Smart Switch use
Audit application installation logs on managed Samsung devices for packages introduced outside of approved stores

Monitoring Recommendations

Enable MDM-based application allowlisting and alert on deviations from approved application baselines
Track Smart Switch version compliance across the mobile fleet through enterprise mobility management reporting
Review physical device access policies and logs for high-risk users and shared or kiosk devices

How to Mitigate CVE-2026-21138

Immediate Actions Required

Update Samsung Smart Switch to version 3.7.73 or later on all affected devices
Restrict physical access to mobile devices, particularly in shared or public environments
Verify application inventories on devices that recently used Smart Switch for data transfer

Patch Information

Samsung addressed this vulnerability in Smart Switch version 3.7.73. Users should install the latest Smart Switch update through the Galaxy Store or Google Play. Refer to the Samsung Mobile Security Advisory for the October 2026 advisory bulletin.

Workarounds

Disable or uninstall Smart Switch on devices that do not require migration functionality
Enforce device lock screens, biometric authentication, and short screen timeouts to reduce physical access risk
Restrict Smart Switch use to supervised scenarios until the patched version is deployed

bash

# Verify installed Smart Switch version via adb
adb shell dumpsys package com.sec.android.easyMover | grep versionName

# Expected output after patch: versionName=3.7.73 (or later)