CVE-2026-21011: Samsung Android Privilege Escalation Flaw

CVE-2026-21011 Overview

CVE-2026-21011 is an incorrect privilege assignment vulnerability in the Bluetooth functionality of Samsung Android devices when operating in Maintenance mode. This security flaw allows physical attackers to bypass the Extend Unlock feature, potentially gaining unauthorized access to the device without proper authentication.

The vulnerability stems from improper permission handling within Samsung's Bluetooth implementation, specifically when the device is in Maintenance mode. An attacker with physical access to the device can exploit this flaw to circumvent the Extend Unlock security mechanism, which is designed to keep devices unlocked when connected to trusted Bluetooth accessories.

Critical Impact

Physical attackers can bypass the Extend Unlock feature on Samsung Android devices, potentially gaining unauthorized access to device contents and sensitive user data.

Affected Products

• Samsung Android 14.0 (all SMR releases prior to April 2026)
• Samsung Android 15.0 (all SMR releases prior to April 2026)
• Samsung Android 16.0 (all SMR releases prior to April 2026)

Discovery Timeline

• April 13, 2026 - CVE-2026-21011 published to NVD
• April 13, 2026 - Last updated in NVD database

Technical Details for CVE-2026-21011

Vulnerability Analysis

This vulnerability is classified under CWE-732 (Incorrect Permission Assignment for Critical Resource), indicating a fundamental flaw in how Samsung's Bluetooth subsystem manages privilege levels during Maintenance mode operations.

The Extend Unlock feature in Samsung Android devices allows users to keep their device unlocked when connected to trusted Bluetooth devices such as smartwatches, car audio systems, or other accessories. When a device enters Maintenance mode—a diagnostic state used for servicing—the Bluetooth component fails to properly enforce the required privilege checks, creating a window for exploitation.

An attacker with physical access to the target device can leverage this misconfiguration to bypass the authentication requirements normally enforced by Extend Unlock, effectively gaining access to the device without providing legitimate credentials or having a trusted Bluetooth device present.

Root Cause

The root cause of CVE-2026-21011 lies in incorrect privilege assignment within Samsung's Bluetooth implementation when the device operates in Maintenance mode. Specifically, the Bluetooth service fails to properly validate and enforce authentication requirements during this operational state, allowing the Extend Unlock security checks to be circumvented.

The vulnerability exists because the privilege escalation boundaries between Maintenance mode and normal operation are not properly segregated. When the device transitions into Maintenance mode, the Bluetooth component incorrectly retains or grants elevated privileges that should be restricted, enabling unauthorized access to protected functionality.

Attack Vector

The attack requires physical access to the target Samsung Android device. The attacker must:

1. Place or wait for the device to enter Maintenance mode
2. Exploit the incorrect privilege assignment in the Bluetooth subsystem
3. Bypass the Extend Unlock authentication mechanism
4. Gain unauthorized access to the device

While physical access is required, limiting the attack surface, the vulnerability is particularly concerning in scenarios involving lost or stolen devices, corporate environments with shared devices, or situations where devices are temporarily left unattended.

The exploitation mechanism targets Samsung's Bluetooth permission model during Maintenance mode, where the expected privilege boundaries are not enforced. This allows the attacker to effectively impersonate a trusted Bluetooth device or bypass the trust verification entirely.

Detection Methods for CVE-2026-21011

Indicators of Compromise

• Unexpected device unlocks without legitimate Bluetooth device connections
• Anomalous Bluetooth connection attempts or pairing activities during Maintenance mode
• Device access logs showing authentication bypasses or unusual unlock patterns
• Evidence of Maintenance mode entry without authorized service intervention

Detection Strategies

• Monitor device logs for Maintenance mode entries that coincide with Bluetooth activity
• Implement Mobile Device Management (MDM) solutions to track device unlock patterns and alert on anomalies
• Deploy endpoint detection solutions capable of monitoring Bluetooth subsystem behavior on Android devices
• Review Samsung Knox audit logs for unauthorized access attempts or privilege escalation events

Monitoring Recommendations

• Enable comprehensive logging on Samsung devices to capture Bluetooth and authentication events
• Configure MDM solutions to alert on unexpected Maintenance mode activations
• Implement SentinelOne Mobile Threat Defense to detect suspicious device state changes and potential exploitation attempts
• Establish baseline device behavior patterns to identify deviations indicative of exploitation

How to Mitigate CVE-2026-21011

Immediate Actions Required

• Update all Samsung Android devices to SMR Apr-2026 Release 1 or later
• Disable Extend Unlock feature on sensitive devices until patching is complete
• Restrict physical access to devices, especially in high-security environments
• Review and audit device access logs for signs of prior exploitation
• Consider disabling Maintenance mode on devices where it is not required

Patch Information

Samsung has addressed this vulnerability in the SMR Apr-2026 Release 1 security maintenance release. Organizations should apply this update immediately to all affected Samsung Android devices running versions 14.0, 15.0, and 16.0.

For detailed patch information, refer to the Samsung Mobile Security Update for April 2026.

Workarounds

• Disable the Extend Unlock feature via Settings > Security > Extend Unlock until the patch is applied
• Implement strong physical security controls for Samsung devices in enterprise environments
• Use Samsung Knox to enforce device policies that restrict Maintenance mode access
• Consider using alternative authentication methods that do not rely on Bluetooth trust relationships

# Samsung device security configuration recommendations
# Disable Extend Unlock via ADB (requires developer options enabled)
adb shell settings put secure trust_agents_extend_unlock 0

# Verify Extend Unlock is disabled
adb shell settings get secure trust_agents_extend_unlock
# Expected output: 0 (disabled)