CVE-2025-4998: H3C Magic R200G Router DOS Vulnerability

CVE-2025-4998 is a denial of service vulnerability in H3C Magic R200G routers affecting multiple WiFi configuration functions. Attackers can remotely trigger service disruption through HTTP POST requests. This article covers technical details, affected versions, impact assessment, and mitigation strategies.

CVE-2025-4998 Overview

CVE-2025-4998 is a denial-of-service vulnerability affecting the H3C Magic R200G router running firmware versions up to 100R002. The flaw resides in the HTTP POST request handler for the /goform/aspForm endpoint. Multiple handler functions including Edit_BasicSSID, Edit_BasicSSID_5G, SetAPWifiorLedInfoById, SetMobileAPInfoById, Asp_SetTimingtimeWifiAndLed, AddMacList, EditMacList, AddWlanMacList, and EditWlanMacList improperly handle the param argument. An attacker with low privileges can trigger the condition remotely over the network. The vendor was contacted about the issue but did not respond, and public disclosure has occurred.

Critical Impact
Remote authenticated attackers can crash the router's web management service, disrupting network availability for all connected clients.

Affected Products

H3C Magic R200G router
Firmware versions up to 100R002
HTTP POST request handler component in /goform/aspForm

Discovery Timeline

2025-05-20 - CVE-2025-4998 published to NVD
2026-06-17 - Last updated in NVD database

Technical Details for CVE-2025-4998

Vulnerability Analysis

The vulnerability is classified under [CWE-404] (Improper Resource Shutdown or Release). It affects the HTTP POST request handler within the router's web management interface. Nine distinct handler functions on the /goform/aspForm endpoint fail to properly validate or bound the param argument. When an attacker submits crafted input to any of these handlers, the router's service enters a state that denies further processing. This impacts device availability without affecting confidentiality or integrity, consistent with the CVSS vector components for availability impact only.

Root Cause

The root cause is improper resource management inside multiple ASP-style form handlers in the H3C proprietary web server binary. The functions Edit_BasicSSID, Edit_BasicSSID_5G, SetAPWifiorLedInfoById, SetMobileAPInfoById, Asp_SetTimingtimeWifiAndLed, AddMacList, EditMacList, AddWlanMacList, and EditWlanMacList do not sanitize or bound-check the param value before consuming it. Manipulated input causes resource exhaustion or an unhandled fault, terminating the handler service.

Attack Vector

The attack is delivered remotely over the network. The attacker must hold low-privilege credentials on the router's web interface. No user interaction is required. Exploitation is limited to a single HTTP POST request directed at /goform/aspForm with a malicious param value targeting one of the affected functions. Public technical write-ups referenced by VulDB Entry #309649 and the GitHub Documentation on H3C R200G describe the request structure.

// Exploitation is described in the public write-up.
// No verified proof-of-concept code is reproduced here.
// Refer to the linked VulDB and GitHub references for technical detail.

Detection Methods for CVE-2025-4998

Indicators of Compromise

Unexpected restarts or unresponsiveness of the H3C Magic R200G web management interface after receiving external HTTP POST traffic.
HTTP POST requests to /goform/aspForm containing anomalous or oversized param values.
Repeated failed authentication attempts followed by targeted requests to the affected handler functions.

Detection Strategies

Inspect HTTP traffic destined to the router management interface for POSTs matching /goform/aspForm with the affected function names listed in the CVE description.
Correlate router service crashes with preceding administrative HTTP POST requests to detect exploitation patterns.
Monitor for scanning activity probing the router web interface from untrusted network segments.

Monitoring Recommendations

Enable syslog forwarding from the router to a centralized log platform to capture web service faults and restart events.
Deploy IDS/IPS signatures targeting the /goform/aspForm URI with abnormal param payloads.
Alert on availability drops of network gateway devices to identify DoS activity affecting connected clients.

How to Mitigate CVE-2025-4998

Immediate Actions Required

Restrict access to the router's web management interface to trusted management VLANs or local administrative hosts only.
Disable remote WAN-side administration if enabled, ensuring the interface is unreachable from the internet.
Rotate administrative credentials and enforce strong passwords to raise the barrier for the required low-privilege authentication.

Patch Information

No vendor patch is available at time of publication. According to the CVE record, the vendor was contacted early about this disclosure but did not respond. Users of the H3C Magic R200G through firmware 100R002 should monitor the VulDB CTI ID #309649 entry for any future vendor advisory.

Workarounds

Place the router management interface behind a firewall ACL that permits only known administrator IP addresses.
Segment the management network from user, guest, and IoT networks to reduce insider exploitation risk.
Consider replacing the affected device with a supported model if the vendor does not release a fix within an acceptable timeframe.

bash

# Example: restrict management access using an upstream firewall
# Allow only trusted admin subnet to reach the router web UI
iptables -A FORWARD -s 192.0.2.0/24 -d <router_ip> -p tcp --dport 80 -j ACCEPT
iptables -A FORWARD -d <router_ip> -p tcp --dport 80 -j DROP