CVE-2021-25337 is an improper access control vulnerability in Samsung Mobile Devices. CISA added it to the Known Exploited Vulnerabilities catalogue on 8 November 2022, which means attackers have used it in real attacks. Samsung mobile devices contain an improper access control vulnerability in clipboard service which allows untrusted applications to read or write arbitrary files.
What this CVE means in practice
CVE-2021-25337 is an improper access control flaw in Samsung Mobile Devices that let untrusted applications read or write arbitrary files through the clipboard service. In practical terms, the vulnerability breaks the trust boundary between an app and device data it should not be able to touch.
That matters because mobile devices often hold messaging data, documents, enterprise apps, browser sessions, and sync material all on the same endpoint. When a service that mediates file access is too permissive, an ordinary-looking app can become a path to broader device compromise, data theft, or tampering.
Why improper access control is dangerous on mobile devices
Access control failures are especially serious on phones because the operating system and apps share a dense local environment, and users commonly grant many apps persistent access to storage, media, and clipboard-like workflows. If an app can overreach inside that environment, the attacker does not need to break encryption or defeat the network first.
For a mobile flaw like this, the risk is not limited to one app’s data. A successful abuse path can expose local files, alter content that other apps rely on, or create misleading or malicious file state that survives normal user interaction. That is why access control bugs on endpoint software are often treated as high-value exploitation opportunities rather than isolated defects.
For the authoritative vulnerability record and version-specific details, readers should consult the CVE Program and the NIST National Vulnerability Database.
How organisations check exposure and reduce blast radius
Exposure review starts with knowing exactly which Samsung device models are in use, where they are managed, and which user groups can install or run untrusted apps. If the fleet is unmanaged or only partially enrolled, the organisation may not know which endpoints are still exposed.
Because this vulnerability can be reached through local app behaviour, internet exposure is less important than endpoint governance, app control, and device posture. Mobile device management, enrolment status, and application allowlisting or restriction become the practical ways to shrink the attack surface on devices that cannot be immediately replaced or upgraded.
Readers can map that operational view to the Mobile Device Security Guide and the Device Trust and Posture Guide, which frame how managed posture and access decisions reduce mobile exposure.
Remediation, detection, and post-exploitation review
Remediation should follow the vendor’s guidance for the affected Samsung devices and prioritise systems that are used for work data, privileged access, or sensitive communications. Where patching is delayed, compensating controls should focus on app restriction, device management, and reducing the set of apps allowed to interact with sensitive local content.
Detection is often about finding the aftermath of abuse rather than a neat signature for the bug itself. Review for suspicious apps, unexpected file access, unusual clipboard activity, abnormal data movement, and changes to local files that do not fit normal user behaviour. If exploitation is suspected, rotate any credentials, tokens, or sessions that may have been exposed through the device.
For broader patch prioritisation and verification discipline, the Vulnerability Management Guide is the most useful internal reference for building the response workflow around a KEV-listed issue.
Risk and Threat Considerations
This CVE matters because it gives an untrusted app a way to cross a local trust boundary and reach files it should not control. On a mobile endpoint, that can turn a low-friction app install or abuse path into data theft, tampering, or a stepping stone to further compromise.
Failure mechanism: A clipboard service that fails to enforce proper access checks can let a malicious or trojanised app read or write arbitrary files, bypassing the intended app sandbox.
Impact: Attackers may steal sensitive local data, alter files used by other apps, or use the endpoint as a foothold for credential theft and wider compromise.
Standards & Framework Alignment
This section maps relevant standards and security frameworks to the operational risks and controls described in this guidance.
NIST SP 800-53 Rev 5 and CIS Controls v8 set the governance and control requirements practitioners need to meet.
| Framework | Control / Reference | Relevance |
|---|---|---|
| NIST SP 800-53 Rev 5 | AC-3 — Access Enforcement | Improper access control directly concerns enforcing authorised file access on devices. |
| AC-6 — Least Privilege | The flaw is dangerous because apps gained more file access than necessary. | |
| SI-2 — Flaw Remediation | A KEV-listed vulnerability requires timely remediation and verification. | |
| Recommendation — Enforce file and service access checks so untrusted apps cannot reach protected resources. Minimise app privileges and restrict local file access to the least necessary scope. Prioritise patching and validate that the vulnerable clipboard service issue is remediated. | ||
| CIS Controls v8 | CIS-4 — Secure Configuration of Enterprise Assets and Software | Mobile device posture and app controls are key compensating measures here. |
| CIS-7 — Continuous Vulnerability Management | KEV-listed mobile flaws should feed prioritisation, remediation, and verification. | |
| Recommendation — Harden mobile software settings and restrict app installation paths that increase exposure. Track affected devices, prioritise remediation, and confirm the exposure is closed. | ||
Practitioner Guidance
Why practitioners should care: Treat this as a device-control problem, not just a single app bug. Mobile endpoints often carry business email, document caches, and authenticated sessions, so one local access-control failure can have outsized downstream impact.
What to watch for: Prioritise devices that are unmanaged, allow broad third-party app installation, or handle sensitive enterprise content. Those are the endpoints where local abuse is most likely to matter operationally.
Practitioner takeaway: When a mobile CVE reaches the KEV catalogue, response should combine vendor patching with endpoint governance, because reducing app freedom is often the fastest compensating control.
Related resources from NHI Mgmt Group
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Reviewed and updated by the NHIMG editorial team on October 17, 2026.
NHI Mgmt Group — the #1 independent authority on Non-Human Identity, IAM, and Agentic AI security. nhimg.org