CVE-2026-21021 Overview
CVE-2026-21021 is an improper input validation vulnerability in the Routines component of Samsung Android. The flaw affects Samsung Android 16.0 builds prior to the Security Maintenance Release (SMR) May-2026 Release 1. An attacker with physical access to an affected device can leverage the weakness to launch privileged activity that should otherwise be restricted. Samsung addressed the issue in the May 2026 Samsung Mobile security bulletin.
Critical Impact
A physical attacker can trigger privileged actions through the Routines feature on unpatched Samsung Android 16.0 devices, bypassing input validation safeguards.
Affected Products
- Samsung Android 16.0 (base release)
- Samsung Android 16.0 SMR releases from August 2025 through April 2026 (inclusive)
- Samsung Routines component on the above builds
Discovery Timeline
- 2026-05-13 - CVE-2026-21021 published to the National Vulnerability Database (NVD)
- 2026-05-13 - Last updated in NVD database
- May 2026 - Samsung releases SMR May-2026 Release 1 addressing the vulnerability
Technical Details for CVE-2026-21021
Vulnerability Analysis
The vulnerability resides in Routines, a Samsung Android feature that automates device actions based on user-defined triggers and conditions. The component fails to properly validate input before processing it, which allows an actor at the device to invoke functionality with elevated privileges. Because the attack vector is physical, exploitation requires hands-on interaction with an unlocked or otherwise accessible handset. The CWE classification is recorded as NVD-CWE-noinfo, indicating Samsung did not disclose granular weakness details. The Exploit Prediction Scoring System (EPSS) places this issue in the lower likelihood band for near-term exploitation, and there are no public proof-of-concept exploits at this time.
Root Cause
The root cause is missing or insufficient input validation within the Routines code path. When user-supplied parameters or action definitions are processed, the component does not adequately constrain them, permitting actions that should require additional authorization to execute. This category of flaw falls under Improper Input Validation.
Attack Vector
Exploitation requires physical access to the target device. The attacker interacts with the Routines interface or related entry points on the device to submit crafted input that triggers privileged behavior. No network access, prior authentication, or user interaction beyond the attacker's own interaction is required. The scope is limited to the device itself, with the primary security impact on availability of system functions controlled through Routines.
No verified exploit code is publicly available. Samsung has not released technical details beyond the brief advisory description in the Samsung Mobile Security Update for May 2026.
Detection Methods for CVE-2026-21021
Indicators of Compromise
- Unexpected Routines configurations or automation rules that the device owner did not create.
- Privileged actions executed on the device without a corresponding user-initiated trigger in system logs.
- Devices found in an unlocked state with the Routines settings or editor screen open.
Detection Strategies
- Audit Samsung Android device build numbers across the mobile fleet to identify endpoints running SMR releases earlier than May-2026 Release 1.
- Use Mobile Device Management (MDM) compliance policies to flag handsets that have not received the May 2026 Samsung patch level.
- Review Routines automation entries during device inspections and forensic triage of suspected lost or recovered devices.
Monitoring Recommendations
- Track Samsung security patch level reporting through MDM telemetry and alert on devices stuck on pre-May-2026 patch strings.
- Monitor for repeated lock-screen interaction or physical tampering events surfaced by enterprise mobility tooling.
- Correlate device handover, loss, and theft reports with patch status to prioritize at-risk handsets for remediation.
How to Mitigate CVE-2026-21021
Immediate Actions Required
- Install the Samsung SMR May-2026 Release 1 update on all affected Samsung Android 16.0 devices.
- Verify the security patch level on each device reads May 1, 2026 or later after the update completes.
- Enforce strong device lock credentials (PIN, password, or biometric) to reduce the window for physical exploitation.
Patch Information
Samsung published the fix in the May 2026 monthly Samsung Mobile security bulletin. Apply the SMR May-2026 Release 1 update through Settings, Software update, Download and install, or distribute the update through the organization's MDM platform. Full advisory details are available in the Samsung Mobile Security Update for May 2026.
Workarounds
- Keep devices locked and physically controlled until the SMR May-2026 Release 1 update is installed.
- Restrict use of the Routines feature on high-risk or shared devices that cannot be promptly updated.
- Apply MDM policies that limit unattended device access in sensitive environments such as conference rooms, kiosks, and shared workstations.
# Verify Samsung Android security patch level via adb
adb shell getprop ro.build.version.security_patch
# Expected output on patched devices: 2026-05-01 or later
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
