CVE-2025-52222: D-Link Router Buffer Overflow DoS Flaw

CVE-2025-52222 Overview

A buffer overflow vulnerability has been discovered in multiple D-Link router firmware versions affecting the radius_asp function. This vulnerability exists when processing several parameters including rd_en, rd_auth, rd_acct, http_hadmin, http_hadminpwd, rd_key, and rd_ip. Attackers can exploit this vulnerability by sending specially crafted requests to cause a Denial of Service (DoS) condition on affected devices.

Critical Impact
Multiple D-Link router models are vulnerable to buffer overflow attacks that can render network devices inoperable through crafted malicious requests.

Affected Products

D-Link DI-8003 v16.07.26A1
D-Link DI-8500 v16.07.26A1
D-Link DI-8003G v17.12.21A1
D-Link DI-8200G v17.12.20A1
D-Link DI-8200 v16.07.26A1
D-Link DI-8400 v16.07.26A1
D-Link DI-8004w v16.07.26A1
D-Link DI-8100 v16.07.26A1
D-Link DI-8100G v17.12.20A1

Discovery Timeline

2026-04-08 - CVE-2025-52222 published to NVD
2026-04-08 - Last updated in NVD database

Technical Details for CVE-2025-52222

Vulnerability Analysis

This buffer overflow vulnerability resides in the radius_asp function within the affected D-Link router firmware. The function fails to properly validate the length of user-supplied input before copying it into fixed-size memory buffers. When an attacker provides oversized values through any of the vulnerable parameters (rd_en, rd_auth, rd_acct, http_hadmin, http_hadminpwd, rd_key, or rd_ip), the resulting memory corruption can crash the device.

The vulnerability affects network routers, which are critical infrastructure devices. A successful attack could disrupt network connectivity for all devices relying on the compromised router. Given that these are IoT/embedded devices with limited security monitoring capabilities, exploitation may go undetected until service disruption occurs.

Root Cause

The root cause of this vulnerability is improper bounds checking in the radius_asp function. The function processes RADIUS authentication configuration parameters without validating input length against buffer boundaries. This classic buffer overflow pattern allows memory beyond the allocated buffer to be overwritten when processing maliciously long parameter values.

Embedded systems like routers often have constrained memory management and may lack modern exploit mitigations such as stack canaries or ASLR, making buffer overflow vulnerabilities particularly impactful on these platforms.

Attack Vector

The attack requires network access to the router's web administration interface. An attacker can craft HTTP requests containing oversized values for the vulnerable parameters in the radius_asp function. These parameters are associated with RADIUS server configuration and administrative credentials.

The vulnerability can be triggered remotely if the router's administration interface is exposed to the network. Attackers send specifically crafted requests with overly long strings in any of the seven vulnerable parameters, causing the buffer overflow condition that leads to device crash or unresponsive state.

For technical details on the vulnerability, refer to the GitHub IoT Vulnerability Collection and the D-Link Security Bulletin.

Detection Methods for CVE-2025-52222

Indicators of Compromise

Unexpected router reboots or unresponsive states without clear cause
Unusual HTTP traffic patterns targeting RADIUS configuration endpoints on router administration interfaces
Network logs showing requests with abnormally long parameter values to router management pages
Service disruptions affecting devices connected through the vulnerable router

Detection Strategies

Monitor HTTP traffic to router administration interfaces for requests containing excessively long parameter values
Implement network intrusion detection rules to identify buffer overflow attack patterns targeting D-Link router management endpoints
Configure alerts for unexpected router restarts or loss of connectivity
Deploy network segmentation to isolate router management interfaces from untrusted networks

Monitoring Recommendations

Enable logging on D-Link routers to capture administrative access attempts
Monitor network traffic for anomalous requests to the RADIUS configuration pages
Implement regular health checks on affected router models to detect DoS conditions
Review access logs for the router administration interface for suspicious activity patterns

How to Mitigate CVE-2025-52222

Immediate Actions Required

Restrict access to router administration interfaces to trusted IP addresses only
Disable remote administration if not required
Implement network segmentation to isolate management interfaces from untrusted networks
Monitor affected devices for signs of exploitation or unexpected behavior
Check the D-Link Security Bulletin for firmware updates

Patch Information

Consult the D-Link Security Bulletin for official patch availability and updated firmware versions for affected router models. Users should apply vendor-provided updates as soon as they become available.

Workarounds

Configure firewall rules to restrict access to the router's web administration interface to specific trusted IP addresses
Disable the web administration interface entirely if not needed and use console-based management
Place affected routers behind a VPN to prevent direct external access to management interfaces
Consider replacing end-of-life devices that may not receive security updates

bash

# Example firewall rule to restrict router management access (adjust IP and port as needed)
# On upstream firewall or network device
iptables -A INPUT -p tcp --dport 80 -s 192.168.1.0/24 -j ACCEPT
iptables -A INPUT -p tcp --dport 80 -j DROP
iptables -A INPUT -p tcp --dport 443 -s 192.168.1.0/24 -j ACCEPT
iptables -A INPUT -p tcp --dport 443 -j DROP