CVE-2026-21098 in Samsung
Summary
by MITRE • 09/09/2026
Improper access control in Link to Windows prior to SMR Sep-2026 Release 1 allows local attackers to establish a connection with the PC without proper user interaction.
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Analysis
by VulDB Data Team • 09/09/2026
The vulnerability identified as an improper access control flaw within the Link to Windows feature, specifically affecting versions prior to the September 2026 Release 1 update, represents a significant security risk for users relying on seamless integration between their mobile devices and personal computers. This defect allows local attackers who have physical or logical access to the system to establish connections with the PC without requiring explicit user interaction such as clicking through permission dialogs or entering authentication credentials. The core technical flaw lies in the failure of the application to enforce strict authorization checks during the initial handshake phase of the connection process, effectively bypassing intended security boundaries that are designed to prevent unauthorized device pairing and data synchronization.
From a technical perspective, this issue stems from insufficient validation mechanisms within the Link to Windows service architecture. When a mobile device attempts to pair with a PC running the affected software version, the system fails to verify whether the user has explicitly granted permission for that specific connection event. This lack of mandatory user consent allows an attacker operating on the local network or having access to the same Wi-Fi segment to initiate and complete a pairing process silently. The vulnerability exploits the trust relationship established by the proximity-based discovery protocol, which is designed for convenience but lacks robust authentication safeguards in its default configuration prior to this patch.
The operational impact of this vulnerability is substantial, as it enables unauthorized access to sensitive data stored on or accessible through the PC. Once a connection is established without user knowledge, an attacker can potentially view notifications, send messages from the phone number associated with the linked device, access photos and files synced via the service, and even control certain aspects of the computer interface remotely. This level of access compromises both confidentiality and integrity, as sensitive personal or corporate information may be exfiltrated to the attacker's mobile device without any indication that a breach has occurred on the host system.
This vulnerability aligns with CWE-284 Improper Access Control, which describes situations where an actor is able to access resources or perform actions for which they should not have been granted permission. Furthermore, it maps closely to MITRE ATT&CK technique T1530 Data from Local System, as the attacker leverages local network proximity and software vulnerabilities to harvest data directly from the compromised endpoint. The absence of user interaction also relates to CWE-798 Use of Hard-coded Credentials or Implicit Trust in certain contexts where the system assumes that any device attempting connection is authorized based on prior pairing history rather than real-time verification.
Mitigation strategies primarily involve applying the vendor-provided update scheduled for September 2026 Release 1, which addresses these access control deficiencies by enforcing explicit user consent mechanisms before allowing new connections. Until such updates are deployed, users should disable automatic connection features within the Link to Windows settings and ensure that only trusted devices are listed in the paired device registry. Additionally, network segmentation can reduce exposure by isolating sensitive PCs from general-purpose Wi-Fi networks where unauthorized pairing attempts might originate. Regular auditing of connected devices and monitoring for unexpected synchronization activities remain critical defensive measures against exploitation of this flaw.