CVE-2026-0021 is a vulnerability identified in the Android operating system, specifically within the hasInteractAcrossUsersFullPermission method of the AppInfoBase.java component. This vulnerability is classified as a confused deputy problem (CWE-441), where the system incorrectly grants permissions across user boundaries. The flaw allows a local attacker, without any prior execution privileges or user interaction, to bypass cross-user permission checks and escalate their privileges on the device. The affected Android versions include 14, 15, 16, and 16-qpr2, covering a broad range of recent Android releases. The vulnerability's CVSS v3.1 base score is 8.4, indicating high severity, with the vector showing local attack vector (AV:L), low attack complexity (AC:L), no privileges required (PR:N), no user interaction (UI:N), unchanged scope (S:U), and high impact on confidentiality, integrity, and availability (C:H/I:H/A:H). This means an attacker with local access can fully compromise the device's security properties. Although no public exploits have been reported yet, the vulnerability's nature and ease of exploitation make it a significant threat. The root cause lies in improper permission validation allowing a confused deputy scenario, where the system component inadvertently grants elevated permissions to a less privileged user or process. This can lead to unauthorized access to sensitive data, modification of system settings, or denial of service. The absence of user interaction and no requirement for prior privileges make this vulnerability particularly dangerous in environments where local access is possible, such as shared devices or those exposed to malicious apps or insiders.

The impact of CVE-2026-0021 is substantial for organizations and individuals relying on affected Android versions. Successful exploitation allows an attacker with local access to escalate privileges without needing any prior permissions or user interaction, potentially leading to full device compromise. This can result in unauthorized access to sensitive data, installation of persistent malware, manipulation or destruction of data, and disruption of device availability. For enterprises, this could mean exposure of corporate data on employee devices, bypassing of mobile device management controls, and lateral movement within networks. In consumer contexts, personal data theft, surveillance, and device misuse are possible. The vulnerability undermines the fundamental security boundaries between users on the device, increasing the risk in multi-user or shared device scenarios. Although no exploits are currently known in the wild, the high severity and ease of exploitation make it a critical risk that could be leveraged by attackers once exploit code becomes available. The broad range of affected Android versions means a large global user base is potentially vulnerable, amplifying the threat's scale.

To mitigate CVE-2026-0021, organizations and users should take the following specific actions: 1) Monitor official Google Android security bulletins and apply patches promptly once they are released for the affected versions (14, 15, 16, and 16-qpr2). 2) Until patches are available, restrict local access to devices by enforcing strong physical security and device lock policies to prevent unauthorized users from gaining local access. 3) Limit installation of untrusted or potentially malicious applications that could exploit local vulnerabilities by enforcing strict app vetting and using mobile device management (MDM) solutions. 4) Employ runtime application self-protection (RASP) or endpoint detection and response (EDR) tools capable of detecting suspicious privilege escalation behaviors on Android devices. 5) Educate users about the risks of granting unnecessary permissions and the importance of device security hygiene. 6) For enterprise environments, consider isolating critical mobile workloads or using containerization to reduce the impact of potential privilege escalations. 7) Review and harden cross-user permission settings and policies where possible to minimize attack surface. These targeted mitigations go beyond generic advice by focusing on controlling local access, monitoring for privilege escalation, and preparing for patch deployment.