CVE-2026-21031 Overview
CVE-2026-21031 is an improper authorization vulnerability [CWE-863] in the AppBlock component of Samsung Android. The flaw affects Samsung Android 15.0 and 16.0 devices prior to the Security Maintenance Release (SMR) Jun-2026 Release 1. A local attacker can launch arbitrary activities that should otherwise be restricted by AppBlock policy. Exploitation requires user interaction, limiting opportunistic attacks but not preventing targeted social engineering scenarios. Samsung disclosed the issue in its June 2026 security bulletin and shipped fixes in the SMR Jun-2026 R1 patch level.
Critical Impact
A local, low-privileged application can bypass AppBlock authorization checks and start arbitrary activities, undermining device-level application restrictions on managed and parental-controlled Samsung devices.
Affected Products
- Samsung Android 15.0 prior to SMR Jun-2026 Release 1
- Samsung Android 16.0 prior to SMR Jun-2026 Release 1
- AppBlock component shipped on Samsung mobile devices
Discovery Timeline
- 2026-06-05 - CVE-2026-21031 published to NVD alongside Samsung's June 2026 SMR bulletin
- 2026-06-06 - Last updated in NVD database
Technical Details for CVE-2026-21031
Vulnerability Analysis
The AppBlock component on Samsung Android enforces restrictions on launching specific applications and activities. These restrictions support parental controls, enterprise management policies, and built-in usage limits. The vulnerability stems from an improper authorization check in AppBlock that fails to validate whether the calling context is permitted to launch a targeted activity. A local attacker holding low privileges on the device can craft an intent that reaches the vulnerable code path and trigger activity launch despite an active block policy. User interaction, such as tapping a prompt or notification, is required to complete the exploitation chain. Successful exploitation results in confidentiality impact on the local device while integrity and availability impact remain limited.
Root Cause
The defect is classified as [CWE-863] Incorrect Authorization. AppBlock evaluates a request to launch an activity but does not correctly verify the authorization state of the caller against the configured block list. The check either trusts attacker-controlled input or evaluates the policy in a way that can be circumvented when a permitted user interaction occurs. The result is an authorization bypass for activity launches that AppBlock is expected to gate.
Attack Vector
Exploitation requires local access to the Samsung device, low-privileged app execution, and a user action to confirm or trigger the activity launch. A malicious application installed on the device, or a benign application abused by an attacker with low privileges, can dispatch the crafted intent. There is no remote attack path and no public proof-of-concept code is available. The vulnerability is not listed in the CISA Known Exploited Vulnerabilities catalog, and no in-the-wild exploitation has been reported.
No verified exploitation code is available. Refer to the Samsung Security Update June 2026 bulletin for vendor technical context.
Detection Methods for CVE-2026-21031
Indicators of Compromise
- Unexpected activity launches from applications that should be restricted by AppBlock policy on managed or parental-controlled devices
- Installation of newly sideloaded or low-reputation applications immediately prior to AppBlock policy violations
- Mobile device management (MDM) logs showing AppBlock policy state changes without a corresponding administrator action
Detection Strategies
- Monitor Samsung Knox or MDM telemetry for activity-launch events that conflict with the configured AppBlock policy
- Audit installed applications on Samsung Android 15.0 and 16.0 devices that have not yet received the SMR Jun-2026 R1 patch level
- Correlate user-interaction events such as notification taps with subsequent launches of blocked activities
Monitoring Recommendations
- Track device patch levels through MDM and flag devices still running pre-Jun-2026 SMR builds
- Alert on policy bypass anomalies surfaced by Samsung Knox audit logs and forward them to the security operations center
- Review enterprise app inventory for applications requesting broad intent or activity-launch capabilities on Samsung devices
How to Mitigate CVE-2026-21031
Immediate Actions Required
- Deploy the Samsung SMR Jun-2026 Release 1 update to all affected Samsung Android 15.0 and 16.0 devices through MDM or end-user prompts
- Inventory the fleet using device management tooling and prioritize devices enrolled in parental control or enterprise AppBlock policies
- Restrict sideloading on managed Samsung devices until the patch is confirmed installed
Patch Information
Samsung addressed CVE-2026-21031 in the SMR Jun-2026 Release 1 firmware update. Patch details and affected build levels are documented in the Samsung Security Update June 2026 advisory. Apply the update through Settings, Software update, Download and install on affected devices, or push the update via enterprise MDM.
Workarounds
- Limit application installation to vetted sources via Samsung Knox or MDM policy until the patch is applied
- Disable user-interaction prompts from untrusted applications where feasible to reduce the chance of triggering the vulnerable path
- Educate users of managed devices to avoid interacting with notifications or prompts from unknown applications
No configuration-only fix is available. The vendor patch is required for full remediation.
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
