CVE-2025-55901: Totolink A3300r Firmware RCE Vulnerability

CVE-2025-55901 Overview

CVE-2025-55901 is a command injection vulnerability [CWE-77] affecting TOTOLINK A3300R routers running firmware version 17.0.0cu.596_B20250515. The flaw resides in the NTPSyncWithHost function, where the host_time parameter passes attacker-controlled input directly into a shell context. An adjacent-network attacker can inject arbitrary operating system commands without authentication. Successful exploitation allows unauthorized modification of router configuration and behavior. The vulnerability was published to the National Vulnerability Database on December 15, 2025.

Critical Impact
Unauthenticated attackers on the adjacent network can execute arbitrary commands on affected TOTOLINK A3300R devices through the host_time parameter of the NTPSyncWithHost function.

Affected Products

TOTOLINK A3300R hardware device
TOTOLINK A3300R firmware version 17.0.0cu.596_B20250515
Deployments exposing the router management interface to adjacent network segments

Discovery Timeline

2025-12-15 - CVE-2025-55901 published to NVD
2026-06-17 - Last updated in NVD database

Technical Details for CVE-2025-55901

Vulnerability Analysis

The vulnerability is a classic command injection issue in the router's NTP synchronization handler. The NTPSyncWithHost function accepts a host_time parameter from an HTTP request and incorporates it into a shell command without sanitization or escaping. Because the parameter value reaches an operating system command interpreter unfiltered, shell metacharacters such as semicolons, backticks, and pipes are interpreted as command separators. Attackers can append arbitrary commands that run with the privileges of the web management process, typically root on embedded Linux routers. No authentication is required, and no user interaction is needed for exploitation.

Root Cause

The root cause is improper neutralization of special elements used in an OS command [CWE-77]. The NTPSyncWithHost handler concatenates the host_time input into a system call rather than passing it as an isolated argument or validating it against an expected numeric or hostname format. This design pattern is common in TOTOLINK firmware handlers that expose configuration functions through CGI endpoints.

Attack Vector

Exploitation requires network adjacency to the router, meaning the attacker must reach the device over the LAN, guest Wi-Fi, or any bridged segment where the management interface is reachable. The attacker sends a crafted request to the vulnerable endpoint containing shell metacharacters in the host_time parameter. The injected payload executes on the device with elevated privileges. The vulnerability impacts integrity, since attackers can modify device state, install persistence, or pivot to other network hosts. For technical details, refer to the GitHub CVE-2025-55901 Document.

Detection Methods for CVE-2025-55901

Indicators of Compromise

HTTP requests to the router management interface containing shell metacharacters (;, |, &&, backticks, $()) in the host_time parameter
Unexpected outbound connections originating from the router to unfamiliar hosts
Unauthorized changes to NTP configuration, DNS settings, or firewall rules on the device
New processes or persistent daemons running on the router outside of vendor firmware baselines

Detection Strategies

Inspect web application firewall or network sensor logs for POST requests to NTP-related CGI endpoints containing non-numeric characters in host_time
Baseline expected router administrative traffic and alert on anomalous request patterns to management interfaces
Monitor DNS and NetFlow telemetry for beaconing behavior from router IP addresses

Monitoring Recommendations

Aggregate router syslog and management-plane logs into a central SIEM for correlation with endpoint telemetry
Alert on configuration changes to NTP, DNS, or administrative accounts on TOTOLINK devices
Track firmware versions across the fleet to identify unpatched A3300R units running 17.0.0cu.596_B20250515

How to Mitigate CVE-2025-55901

Immediate Actions Required

Restrict access to the router administrative interface to trusted management VLANs only
Disable remote administration and guest-network access to the LAN management port
Change default administrative credentials and rotate any credentials exposed to untrusted users
Audit A3300R devices for signs of unauthorized configuration changes or unknown running processes

Patch Information

At the time of publication, no vendor advisory or firmware update has been listed in the CVE record. Monitor the TOTOLINK official website for security bulletins and firmware releases addressing the NTPSyncWithHost command injection.

Workarounds

Segment the router onto a management VLAN accessible only from administrative hosts
Block untrusted clients from reaching the router's HTTP management interface using upstream ACLs
Replace affected A3300R units with patched devices if the vendor does not release a firmware update in a reasonable timeframe

bash

# Example: restrict router management interface access with iptables on an upstream gateway
iptables -A FORWARD -s 192.0.2.0/24 -d <router_ip> -p tcp --dport 80 -j DROP
iptables -A FORWARD -s 10.0.10.0/24 -d <router_ip> -p tcp --dport 80 -j ACCEPT