CVE-2021-25394 (Samsung Mobile Devices Race Condition)

What this vulnerability means in practice

This CVE is a race condition in Samsung mobile devices, which means the vulnerable code can be pushed into an unsafe sequence of operations. In this case, that unsafe timing issue sits in the MFC charger driver and can turn into a use-after-free, so the defect is not just theoretical, it can create a write primitive once the relevant radio privilege is compromised.

Race conditions are dangerous because security checks and memory handling are often designed around an assumed order of events. If an attacker can influence timing, they may cause a resource to be freed while another part of the system still expects it to exist, which can destabilise the device or give the attacker leverage to manipulate memory.

Why mobile drivers make race conditions high impact

Kernel and driver code runs close to the operating system core, so timing bugs there tend to have outsized consequences. A flaw in a charger driver may look narrow, but mobile platforms often expose many interconnected components, and a memory-safety failure in one driver can become a broader device compromise path if the attacker can reach it through the right privilege boundary.

On mobile systems, the practical concern is not only crash risk. If a race condition becomes a use-after-free, the security boundary can shift from a logic error to memory corruption, which is the kind of condition that attackers often look for because it can support escalation or code execution rather than a simple denial of service.

How organisations check exposure and confirm remediation

Exposure review starts with knowing exactly where the affected Samsung devices exist, whether they are internet-facing through management tooling, and whether they are still receiving security updates. Organisations should check vendor advisories and the NIST National Vulnerability Database alongside the CVE Program record, then reconcile that information against their own mobile inventory and patch status.

For prioritisation, a KEV-listed issue deserves faster handling than an ordinary disclosure because exploitation has already been observed. If remediation is delayed, organisations should treat the device set as time-sensitive exposure and verify whether compensating controls, such as tighter device management policy or temporary access restrictions, reduce the reachable attack surface.

Detection, compromise review, and identity impact

After patching, teams should review whether the vulnerable devices showed signs of unusual instability, unexpected reboots, driver faults, or other behaviour that could indicate exploitation attempts. A post-patch review matters because memory corruption bugs can be used to gain more than a one-off crash, and evidence of exploitation may persist even after the code is fixed.

If exploitation is suspected, the identity impact may extend beyond the device itself. Mobile compromise can expose sessions, tokens, enrolled accounts, or privileged access paths bound to the handset, so the incident review should include any credentials or access material that could have been used from that device and should be rotated or revoked where compromise is plausible.

Risk and Threat Considerations

This vulnerability matters because race conditions in low-level mobile code can be converted into memory corruption and, in the wrong conditions, into attacker-controlled writes. Once that happens, the issue can move from a reliability bug to an exploitation path that supports deeper device compromise.

Failure mechanism: An attacker forces the vulnerable code into an unsafe timing window, causing the driver to reuse or free memory at the wrong moment and creating a use-after-free.

Impact: The attacker may gain a write primitive, which can enable escalation, persistence, or further compromise of the mobile device.

Practitioner Guidance

Why practitioners should care: KEV-listed mobile vulnerabilities should be treated as operationally urgent because real-world exploitation is already established. The right response is to identify every exposed Samsung device, confirm patch status, and decide quickly whether any higher-risk devices need temporary containment while remediation is underway.

What to watch for: Prioritise devices that are unmanaged, delayed on updates, or connected to sensitive enterprise accounts, because those are the devices most likely to turn a local software flaw into a broader organisational incident.

Related resources from NHI Mgmt Group

• CVE-2025-21042 (Samsung Mobile Devices Out-of-Bounds Write)
• CVE-2025-21043 (Samsung Mobile Devices Out-of-Bounds Write)
• CVE-2022-22265 (Samsung Mobile Devices Use-After-Free)
• How should organisations govern private AI apps used on mobile devices?