Introduction
If you use an outdated version of Smart Switch, an attacker on the same WiFi network can get at the backup data from your Samsung device. CVE-2025-21078 comes from a single cryptographic mistake, and that mistake is enough to break the confidentiality of sensitive user data during wireless transfers. It matters most to organizations and individuals who use Smart Switch to migrate devices or run backups, especially where devices often share a network with strangers.
Samsung Smart Switch is a widely used app for moving data between Samsung devices. It handles both wired and wireless transfers, and millions of users worldwide rely on it. Because it is popular and built into Samsung's device ecosystem, a Smart Switch vulnerability can reach a large share of Samsung's mobile users.
Technical Information
CVE-2025-21078 affects Samsung Smart Switch versions prior to 3.7.68.6. The app uses insufficiently random values to generate the secretKey parameter, which protects backup data during wireless transfers. The random number generator that creates secretKey does not supply enough entropy, so an attacker with network adjacency can predict the resulting key values.
The issue is classified under CWE-330 (Use of Insufficiently Random Values). In practice, an attacker on the same network segment as the victim can observe or infer the secretKey used during a Smart Switch wireless transfer. With statistical analysis or brute force, the attacker can predict the secretKey and read the backup data in transit without authorization. The attack does not require prior compromise of the device, and it needs no user interaction beyond being present on the same network while the transfer happens.
The root cause is that the app either does not use a cryptographically secure pseudo-random number generator (CSPRNG) or does not seed the generator with enough entropy. Either way, the secretKey space is small enough that predicting or brute-forcing a key is feasible. No public code snippets or detailed PoC are available for this vulnerability.
Patch Information
Samsung's November 2025 security update fixed several vulnerabilities across its apps and services. One of those fixes is in the Samsung Account application, which mishandled insufficient permissions or privileges. A local attacker who could interact with the device could use that flaw to access sensitive data in Samsung Account.
Samsung fixed it in version 15.5.00.18 of the Samsung Account app by adding stronger authorization checks, so only users with the appropriate permissions can access specific data.
Patch source: Samsung Mobile Security November 2025
Affected Systems and Versions
- Samsung Smart Switch versions prior to 3.7.68.6 are affected
- All configurations using wireless transfer on these versions are vulnerable
- Versions 3.7.68.6 and later are not affected
Vendor Security History
Smart Switch has had several notable vulnerabilities in 2025, including authentication bypass and improper protection of backup data. Samsung ships security updates on a regular monthly cycle and has released patches promptly for reported vulnerabilities. Still, cryptographic and authentication flaws keep turning up in Smart Switch, which suggests ongoing problems with secure development and threat modeling for this app.
