A newly disclosed use-after-free vulnerability in Apache NuttX RTOS could allow attackers to cause system crashes and unintended filesystem operations, prompting urgent security warnings for users running network-exposed services.

The flaw, tracked as CVE-2025-48769 and rated moderate in severity, affects a wide range of NuttX versions and was publicly disclosed on December 31, 2025.

The vulnerability resides in the fs/vfs/fs_rename code of Apache NuttX, a mature real-time embedded operating system widely used in 8-bit to 64-bit microcontroller environments.

The security issue stems from a recursive implementation that uses a single buffer with two different pointer variables.

Enabling arbitrary user-provided size buffer reallocation and write operations to previously freed heap chunks.

Field	Details
CVE ID	CVE-2025-48769
Vulnerability Type	Use After Free (CWE-416)
Affected Product	Apache NuttX RTOS
Affected Component	Virtual File System (VFS) – `fs/vfs`

This use-after-free condition can trigger unintended virtual filesystem rename and move operations, potentially leading to system instability and crashes in specific scenarios.

Users operating virtual filesystem-based services with write access face a particular risk, especially when these services are exposed over network protocols such as FTP.

The vulnerability affects all Apache NuttX RTOS versions from 7.20 through 12.10.0. The Apache NuttX development team has released version 12.11.0, which includes comprehensive fixes addressing the security flaw.

Organizations running affected versions are strongly recommended to upgrade immediately to eliminate the risk of exploitation.

The vulnerability was discovered and reported by Richard Jiayang Liu from the University of Illinois, who also contributed to developing the remediation code.

The security fix underwent rigorous review by NuttX maintainers Xiang Xiao and Jiuzhu Dong before integration into the codebase.

Tomek Cedro from Apache coordinated the disclosure process, ensuring timely notification and patch availability.

No active exploitation has been reported in the wild, though the moderate severity rating underscores the importance of prompt patching.

Organizations unable to immediately upgrade should consider implementing network-level access controls to restrict write access to virtual filesystem services.

In particular, FTP servers, until the security update is deployed across affected embedded systems and IoT devices.

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