CVE-2026-21134 in Flow
Summary
by MITRE • 10/12/2026
Improper authentication in Samsung Flow prior to version 4.9.22.4 allows adjacent attackers to access sensitive information.
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Analysis
by VulDB Data Team • 10/12/2026
The vulnerability identified as an improper authentication flaw within Samsung Flow versions prior to 4.9.22.4 represents a critical security deficiency that undermines the integrity of user data protection mechanisms on affected devices. This issue stems from insufficient verification protocols during local interactions, specifically allowing adjacent attackers who have physical or near-field proximity access to bypass standard authentication checks. In practical terms, this means an attacker does not need valid credentials such as passwords, PINs, or biometric confirmations to interact with the application's sensitive functions. The flaw likely resides in how the service handles session tokens or local API calls when initiated from trusted devices within a paired ecosystem, failing to enforce strict identity validation for every privileged operation.
From a technical perspective, this vulnerability aligns closely with CWE-287, which categorizes improper authentication as a failure of an application to correctly verify that a user is who they claim to be before granting access to resources. The attack vector typically involves leveraging the trust relationship established between paired devices, such as smartphones and tablets or computers running Samsung Flow software. An adjacent attacker could exploit this by initiating unauthorized requests through local network protocols like Bluetooth Low Energy or Wi-Fi Direct, depending on the specific implementation of the proximity-based features. By manipulating these communication channels, the adversary can trick the application into executing commands that retrieve personal messages, photos, clipboard contents, or other sensitive data without triggering a secondary authentication prompt.
The operational impact of this vulnerability is significant for end-users who rely on Samsung Flow for seamless productivity across multiple devices. Unauthorized access to sensitive information can lead to severe privacy violations and potential identity theft if the exposed data includes personally identifiable information or corporate secrets. For enterprise environments, this flaw poses a risk to organizational security policies by allowing unauthorized individuals with physical proximity to exfiltrate confidential business communications stored on synced devices. The ability of an adjacent attacker to access this data without detection compromises the confidentiality aspect of the CIA triad and erodes trust in the device's ecosystem integrity.
Mitigation strategies primarily involve updating the Samsung Flow application to version 4.9.22.4 or later, where these authentication checks have been strengthened to require explicit user confirmation for sensitive operations even within trusted local networks. Administrators should enforce patch management policies that ensure all endpoints running this software are kept up to date with the latest security patches from Samsung. Additionally, users can reduce their exposure by disabling unnecessary proximity-based features when not in use and ensuring that only known, secure devices are paired with their primary accounts. Monitoring for unusual activity or unauthorized sync events can also help detect potential exploitation attempts early.
This vulnerability is relevant to several ATT&CK techniques related to lateral movement and data exfiltration within local networks. Specifically, it relates to T1021.005 which covers Remote Services via Bluetooth, as the attack relies on adjacent wireless connections to establish unauthorized access. It also touches upon T1530 Data from Local System where sensitive files are read without proper authorization. Understanding these mappings helps security teams prioritize remediation efforts and monitor for indicators of compromise associated with local privilege escalation or data theft using legitimate system tools abused through authentication bypasses.