CVE-2026-21004: Smart Switch DoS Vulnerability

CVE-2026-21004 Overview

CVE-2026-21004 is an improper authentication vulnerability affecting Samsung Smart Switch prior to version 3.7.69.15. This security flaw allows adjacent network attackers to trigger a denial of service condition on affected devices. The vulnerability stems from insufficient authentication mechanisms that fail to properly validate requests from nearby network entities.

Critical Impact

Adjacent network attackers can exploit improper authentication to cause denial of service, disrupting Smart Switch functionality and potentially affecting device data migration operations.

Affected Products

• Samsung Smart Switch versions prior to 3.7.69.15

Discovery Timeline

• 2026-03-16 - CVE CVE-2026-21004 published to NVD
• 2026-03-16 - Last updated in NVD database

Technical Details for CVE-2026-21004

Vulnerability Analysis

This improper authentication vulnerability in Samsung Smart Switch allows attackers positioned on the same local network segment to bypass authentication controls and trigger denial of service conditions. The flaw exists in versions prior to 3.7.69.15 and requires user interaction to exploit, though the attack complexity is low once an attacker has adjacent network access.

The vulnerability primarily impacts availability, with no direct effect on confidentiality or integrity of data. When exploited, the Smart Switch application becomes unresponsive or crashes, preventing users from completing device-to-device data transfers.

Root Cause

The root cause of CVE-2026-21004 lies in improper authentication implementation within the Smart Switch application's network communication handlers. The application fails to adequately verify the authenticity of requests received from adjacent network sources, allowing malicious actors on the same network segment to send crafted requests that bypass authentication checks.

Attack Vector

The attack requires the adversary to be on an adjacent network (such as the same Wi-Fi network or local subnet) as the target device running Smart Switch. The attacker does not need any special privileges to execute the attack, but some form of user interaction is required on the target device. Once these conditions are met, the attacker can send specially crafted network requests that exploit the improper authentication mechanism.

The adjacent network attack vector means this vulnerability cannot be exploited remotely over the internet, limiting the exposure to scenarios where the attacker has local network proximity to the victim. This includes shared corporate networks, public Wi-Fi environments, or compromised home networks.

Detection Methods for CVE-2026-21004

Indicators of Compromise

• Unexpected Smart Switch application crashes or unresponsive behavior during normal operation
• Anomalous network traffic patterns targeting Smart Switch communication ports from adjacent devices
• Multiple authentication-related errors in Smart Switch application logs

Detection Strategies

• Monitor network traffic for unusual patterns targeting Smart Switch services from local network sources
• Implement endpoint detection rules to identify repeated Smart Switch crashes or restarts
• Deploy network intrusion detection systems (IDS) to flag suspicious adjacent network activity

Monitoring Recommendations

• Enable verbose logging on Smart Switch if available to capture authentication failures
• Monitor device application health for Smart Switch stability issues
• Review network logs for unexpected local network communications to mobile devices

How to Mitigate CVE-2026-21004

Immediate Actions Required

• Update Samsung Smart Switch to version 3.7.69.15 or later immediately
• Avoid using Smart Switch on untrusted or public Wi-Fi networks until patched
• Temporarily disable Smart Switch when not actively performing device migrations
• Ensure mobile devices are connected only to trusted network environments

Patch Information

Samsung has addressed this vulnerability in Smart Switch version 3.7.69.15. Users should update to this version or later through the official Samsung app store or device update mechanisms. Detailed patch information is available through the Samsung Mobile Security Update advisory page.

Workarounds

• Disable Smart Switch when not in active use to reduce attack surface
• Only use Smart Switch on trusted, private networks with known devices
• Consider using USB-based data transfer instead of network-based methods when on untrusted networks
• Enable network isolation features on routers to prevent lateral movement between devices