CVE-2025-48769 is a Use After Free vulnerability (CWE-416) identified in the Apache NuttX Real-Time Operating System (RTOS), specifically within the virtual filesystem (VFS) rename functionality implemented in fs/vfs/fs_rename. The root cause stems from a recursive implementation that uses a single buffer referenced by two different pointer variables. This design flaw allows an attacker to trigger arbitrary user-controlled buffer reallocations and write operations to a previously freed heap chunk. Such memory corruption can cause unintended side effects in virtual filesystem rename or move operations, potentially leading to inconsistent filesystem states or unexpected behavior. The vulnerability affects all Apache NuttX versions starting from 7.20 up to but not including 12.11.0, where the issue has been fixed. The vulnerability is exploitable remotely without authentication or user interaction, particularly when virtual filesystem services with write access are exposed over the network, for example via FTP servers running on devices using NuttX. While the CVSS score is moderate (5.3), the impact is limited to confidentiality loss with no direct integrity or availability compromise reported. No known exploits have been observed in the wild to date. The vulnerability highlights risks in embedded and IoT devices relying on Apache NuttX RTOS for networked filesystem operations.

For European organizations, the primary impact of CVE-2025-48769 lies in embedded and IoT devices running Apache NuttX RTOS that expose virtual filesystem services with write capabilities over networks. Potential unintended rename or move operations could disrupt device file management, leading to data inconsistency or leakage of sensitive information. While the vulnerability does not directly compromise system integrity or availability, it could be leveraged as a foothold for further attacks or cause operational anomalies in critical infrastructure devices. Sectors such as manufacturing, energy, transportation, and healthcare that deploy NuttX-based embedded systems are at risk, especially if devices are accessible remotely without adequate network segmentation or access controls. The moderate CVSS score reflects the limited but non-negligible risk, emphasizing the need for timely patching to prevent exploitation. The absence of known exploits reduces immediate threat but does not eliminate future risk, particularly as attackers often target embedded RTOS vulnerabilities.

European organizations should immediately identify all devices and systems running Apache NuttX RTOS versions from 7.20 up to before 12.11.0, focusing on those exposing virtual filesystem services with write access over the network. The primary mitigation is to upgrade affected systems to Apache NuttX RTOS version 12.11.0 or later, where the vulnerability is resolved. For devices that cannot be immediately patched, network-level mitigations should be applied, including restricting access to vulnerable services via firewalls, VPNs, or network segmentation to limit exposure. Disabling unnecessary virtual filesystem services or write access over the network can reduce attack surface. Monitoring device logs and network traffic for anomalous rename or filesystem operations may help detect exploitation attempts. Additionally, implementing strict access controls and authentication for network-exposed services will mitigate unauthorized exploitation. Vendors and integrators should review their embedded device firmware and update release processes to incorporate this patch promptly.