CVE-2026-21009: 
NixOS vulnerability analysis and mitigation

CVE-2026-21009 is an improper check for exceptional conditions (CWE-754) in the Samsung Android Recents component that allows a physical attacker to bypass the App Pinning security feature. It affects Samsung Android versions 14, 15, and 16 prior to the SMR Apr-2026 Release 1 security update. The vulnerability was published on April 13, 2026, by Samsung Mobile. It carries a CVSS v3.1 base score of 6.8 (Medium) and a CVSS v4.0 base score of 4.1 (Medium) (Samsung Advisory, GitHub Advisory).

The root cause is improper handling of unusual or exceptional conditions (CWE-754) within the Recents (recent apps) subsystem of Samsung's Android overlay. App Pinning is a security feature that locks the device to a single application, preventing access to other apps or device functions without authentication; the flaw allows this restriction to be circumvented through an unspecified exceptional condition triggered via physical interaction with the device. Exploitation requires no privileges and no user interaction beyond physical access to the device, but attack requirements note that specific deployment/execution conditions must be present (Samsung Advisory, GitHub Advisory).

Successful exploitation allows a physically present attacker to escape the App Pinning lock, gaining unauthorized access to applications and data that the device owner intended to restrict. The primary impact is a high confidentiality risk — an attacker with physical access to a pinned device (e.g., a kiosk, a borrowed or stolen phone) could navigate freely to other apps and access sensitive personal or corporate data. Integrity and availability of the vulnerable system are not directly impacted according to the CVSS v4.0 assessment (Samsung Advisory, GitHub Advisory).

There is no public proof-of-concept exploit and no evidence of in-the-wild exploitation at this time (GitHub Advisory). The EPSS score is approximately 0.022% (1st percentile), indicating a very low probability of exploitation in the near term. The vulnerability is not listed in the CISA Known Exploited Vulnerabilities (KEV) catalog. Exploitation is inherently limited by the physical access requirement, significantly reducing the attacker pool.

Samsung has addressed this vulnerability in the SMR Apr-2026 Release 1 security update for Android 14, 15, and 16. Users and administrators should apply the April 2026 Samsung security patch as soon as it is available for their device model. As an interim measure, organizations should enforce physical security controls to prevent unauthorized access to Samsung devices where App Pinning is relied upon as a security boundary. Mobile device management (MDM) policies should be reviewed to ensure App Pinning is not the sole access control for sensitive deployments (Samsung Advisory).

Coverage of CVE-2026-21009 has been limited to automated vulnerability tracking and aggregation sites, with no notable independent researcher commentary or significant media coverage identified. The vulnerability was noted in Samsung's April 2026 security bulletin and picked up by standard CVE feed services shortly after publication (GitHub Advisory, Samsung Advisory).