CVE-2026-20999: Smart Switch Auth Bypass Vulnerability

CVE-2026-20999 Overview

CVE-2026-20999 is an authentication bypass vulnerability affecting Samsung Smart Switch software prior to version 3.7.69.15. This flaw enables remote attackers to bypass authentication mechanisms through replay attacks, allowing them to trigger privileged functions without proper authorization.

Critical Impact

Remote attackers can exploit this authentication bypass to execute privileged functions on affected Smart Switch installations, potentially compromising device security and data integrity.

Affected Products

• Samsung Smart Switch versions prior to 3.7.69.15

Discovery Timeline

• 2026-03-16 - CVE-2026-20999 published to NVD
• 2026-03-16 - Last updated in NVD database

Technical Details for CVE-2026-20999

Vulnerability Analysis

This authentication bypass vulnerability allows attackers to capture and replay authentication tokens or session credentials to gain unauthorized access to privileged functions within Smart Switch. The vulnerability exists in how the application handles authentication requests, failing to properly validate the freshness or uniqueness of authentication data.

Replay attacks work by intercepting legitimate authentication communications and then retransmitting them to the target system. In the case of CVE-2026-20999, the Smart Switch application does not implement adequate anti-replay mechanisms such as nonces, timestamps with tight windows, or sequence numbers, allowing previously captured authentication data to be reused.

The network-based attack vector means that an attacker positioned to intercept network traffic between the user and the Smart Switch service can capture valid authentication sequences and replay them to gain the same level of access as the legitimate user.

Root Cause

The root cause of this vulnerability is the absence of proper anti-replay protections in the authentication mechanism. The Smart Switch application fails to implement cryptographic measures that would detect and reject replayed authentication requests, such as challenge-response protocols with unique nonces or time-bound tokens with strict validation windows.

Attack Vector

The attack can be executed remotely over the network. An attacker must first capture valid authentication traffic through network interception techniques such as man-in-the-middle positioning, packet sniffing on shared networks, or compromised network infrastructure. Once authentication data is captured, the attacker can replay these credentials to authenticate as the victim user and access privileged functionality.

The vulnerability requires some user interaction, as a legitimate user must first initiate an authentication sequence that the attacker can capture. However, once captured, the replayed credentials can be used without further user involvement.

Detection Methods for CVE-2026-20999

Indicators of Compromise

• Multiple authentication attempts using identical authentication tokens or credentials from different source IP addresses
• Authentication requests with anomalous timing patterns indicating replayed sessions
• Unexpected privileged function executions following authentication from unfamiliar network locations

Detection Strategies

• Implement network monitoring to detect duplicate authentication packets within short time windows
• Deploy intrusion detection rules to identify authentication replay patterns in Smart Switch traffic
• Monitor for authentication anomalies such as identical session tokens being used from geographically disparate locations

Monitoring Recommendations

• Enable comprehensive logging for all Smart Switch authentication events and privileged function calls
• Establish baseline authentication patterns to identify deviations that may indicate replay attacks
• Configure alerting for authentication attempts that exhibit characteristics of replay attacks

How to Mitigate CVE-2026-20999

Immediate Actions Required

• Update Samsung Smart Switch to version 3.7.69.15 or later immediately
• Audit recent authentication logs for signs of replay attack exploitation
• Implement network segmentation to reduce exposure of Smart Switch traffic to potential interception

Patch Information

Samsung has addressed this vulnerability in Smart Switch version 3.7.69.15. Users should update to this version or later to remediate the authentication bypass vulnerability. For detailed patch information, refer to the Samsung Security Bulletin March 2026.

Workarounds

• Restrict Smart Switch usage to trusted networks where traffic interception is less likely
• Avoid using Smart Switch on public or untrusted Wi-Fi networks until the patch is applied
• Consider implementing additional network-level encryption (VPN) when using Smart Switch on potentially exposed networks