CVE-2026-77853: FF-RFI079I4/FF-RFI078I4 RCE Vulnerability

CVE-2026-77853 Overview

CVE-2026-77853 is an OS command injection vulnerability affecting Lite-On FlexFi FF-RFI079I4 and FF-RFI078I4 radio units. The flaw exists in the Management Plane (M-Plane) accessed via the Network Configuration Protocol (NETCONF). An authenticated user who can log in to the M-Plane may execute arbitrary operating system commands on the underlying device. The vulnerability is classified under CWE-78: Improper Neutralization of Special Elements used in an OS Command. Successful exploitation grants attackers the ability to run commands with the privileges of the NETCONF service, potentially compromising the confidentiality, integrity, and availability of the radio unit.

Critical Impact
Authenticated attackers with M-Plane access can execute arbitrary OS commands on affected FlexFi radio units, potentially disrupting 5G radio access network operations.

Affected Products

Lite-On FlexFi FF-RFI079I4 radio unit
Lite-On FlexFi FF-RFI078I4 radio unit
Devices exposing the M-Plane NETCONF interface

Discovery Timeline

2026-09-15 - CVE-2026-77853 published to NVD
2026-09-16 - Last updated in NVD database

Technical Details for CVE-2026-77853

Vulnerability Analysis

The vulnerability resides in the M-Plane NETCONF interface of the FF-RFI079I4 and FF-RFI078I4 radio units. NETCONF is the standard protocol used to manage O-RAN radio unit configuration. The affected implementation fails to properly neutralize special shell metacharacters in operational parameters before passing them to an OS command interpreter.

An authenticated user with M-Plane credentials can inject shell metacharacters such as ;, |, &, or backticks into RPC payloads. The injected characters break out of the intended command context and execute attacker-controlled commands on the device operating system. The attack requires network reachability to the M-Plane and valid low-privilege credentials, but no user interaction.

Root Cause

The root cause is missing input sanitization in the NETCONF request handler. User-supplied strings are concatenated directly into shell command lines invoked by the management daemon. The device does not apply an allow-list, escape shell metacharacters, or use parameterized process invocation such as execve with separated arguments.

Attack Vector

Exploitation requires network access to the M-Plane, which is typically deployed on an isolated management network within an Open Radio Access Network (O-RAN) fronthaul segment. An attacker who has obtained valid NETCONF credentials, or who has pivoted from another compromised management host, submits a crafted NETCONF edit-config or RPC operation containing shell metacharacters. The injected payload runs with the privileges of the process that services NETCONF requests, often permitting full device takeover.

No public proof-of-concept code is available. See the JVN Security Vulnerability Report and the Lite-On Security Overview for vendor-specific technical detail.

Detection Methods for CVE-2026-77853

Indicators of Compromise

Unexpected NETCONF RPC payloads containing shell metacharacters such as ;, |, &&, or backticks in configuration leaf values
New or unexpected child processes spawned by the NETCONF management daemon on affected radio units
Outbound network connections from radio units to non-management destinations
Modifications to system files, cron entries, or startup scripts on the radio unit

Detection Strategies

Enable verbose NETCONF audit logging and forward it to a centralized log platform for anomaly analysis
Correlate authentication events on the M-Plane with subsequent RPC operations to identify suspicious sessions
Alert on NETCONF configuration values that contain shell metacharacters or encoded command sequences

Monitoring Recommendations

Monitor the fronthaul management VLAN for unauthorized NETCONF sessions and unusual source addresses
Track process creation on the radio unit management operating system where telemetry is available
Review vendor advisories from the Lite-On Security Overview portal for updated indicators

How to Mitigate CVE-2026-77853

Immediate Actions Required

Restrict M-Plane NETCONF access to a dedicated, isolated management network with strict access control lists
Rotate all NETCONF credentials on affected FF-RFI079I4 and FF-RFI078I4 units and enforce strong, unique passwords
Audit accounts authorized to log in to the M-Plane and remove unnecessary users
Apply vendor-provided firmware updates as soon as Lite-On publishes remediated versions

Patch Information

Refer to the Lite-On FlexFi security page and the JVN advisory JVN02049764 for the current status of firmware updates addressing CVE-2026-77853. Apply the vendor-recommended firmware to all deployed FF-RFI079I4 and FF-RFI078I4 units following standard change-control procedures for the radio access network.

Workarounds

Segment the fronthaul management network so that only authorized Distributed Unit (DU) and element management hosts can reach the M-Plane
Enforce mutual TLS or SSH transport for NETCONF sessions and disable any unauthenticated management channels
Implement session logging and rate limiting on NETCONF endpoints to reduce brute-force and abuse opportunities

bash

# Example ACL restricting NETCONF (TCP/830) to a management jump host
iptables -A INPUT -p tcp --dport 830 -s 10.10.20.5 -j ACCEPT
iptables -A INPUT -p tcp --dport 830 -j DROP