CVE-2025-5408: WAVLINK Routers Buffer Overflow Vulnerability

CVE-2025-5408 Overview

A critical buffer overflow vulnerability has been identified in multiple WAVLINK router models, affecting the HTTP POST Request Handler component. The vulnerability exists in the sys_login function within /cgi-bin/login.cgi, where improper handling of the login_page argument allows attackers to trigger a buffer overflow condition. This flaw can be exploited remotely without authentication, potentially allowing attackers to execute arbitrary code or crash the affected device.

Critical Impact
Remote attackers can exploit this buffer overflow vulnerability to compromise WAVLINK routers, potentially gaining complete control over affected devices and the networks they manage.

Affected Products

WAVLINK QUANTUM D2G (up to firmware V1410_240222)
WAVLINK QUANTUM D3G (up to firmware V1410_240222)
WAVLINK WL-WN530G3A (up to firmware V1410_240222)
WAVLINK WL-WN530HG3 (up to firmware V1410_240222)
WAVLINK WL-WN532A3 (up to firmware V1410_240222)
WAVLINK WL-WN576K1 (up to firmware V1410_240222)

Discovery Timeline

2025-06-01 - CVE-2025-5408 published to NVD
2025-06-02 - Last updated in NVD database

Technical Details for CVE-2025-5408

Vulnerability Analysis

This vulnerability is classified under CWE-119 (Improper Restriction of Operations within the Bounds of a Memory Buffer). The flaw resides in the authentication mechanism of the affected WAVLINK routers, specifically within the login handling functionality. When processing HTTP POST requests to the /cgi-bin/login.cgi endpoint, the sys_login function fails to properly validate the bounds of the login_page parameter before copying data into a fixed-size buffer.

The vulnerability can be exploited remotely over the network without requiring any authentication or user interaction. An attacker who successfully exploits this vulnerability could achieve full compromise of the device, including the ability to execute arbitrary code with elevated privileges, modify device configurations, intercept network traffic, or use the compromised router as a pivot point for further attacks within the network.

Root Cause

The root cause of this vulnerability is improper bounds checking in the sys_login function when handling the login_page argument. The function allocates a fixed-size buffer for storing user-supplied input but does not validate that the input length falls within acceptable boundaries before performing memory operations. This classic buffer overflow pattern allows an attacker to write data beyond the allocated buffer space, potentially overwriting adjacent memory including return addresses or function pointers.

Attack Vector

The attack can be launched remotely via network-accessible HTTP POST requests to the vulnerable endpoint. An attacker would craft a malicious HTTP POST request to /cgi-bin/login.cgi containing an oversized login_page parameter. When the sys_login function processes this request, the oversized input overflows the destination buffer, potentially allowing the attacker to:

Corrupt adjacent memory structures
Overwrite return addresses to redirect execution flow
Inject and execute arbitrary shellcode
Cause denial of service through device crash

The vulnerability is particularly dangerous because it exists in the authentication handler, meaning no prior authentication is required to trigger the overflow. Technical details and proof-of-concept information have been disclosed publicly through the GitHub Documentation.

Detection Methods for CVE-2025-5408

Indicators of Compromise

Unusual HTTP POST requests to /cgi-bin/login.cgi with abnormally large login_page parameters
Unexpected router reboots or crashes without administrative action
Anomalous outbound network connections originating from the router
Unauthorized configuration changes or new administrative accounts on the device

Detection Strategies

Monitor HTTP traffic for POST requests to /cgi-bin/login.cgi containing payloads exceeding normal login parameter sizes
Implement intrusion detection rules to flag buffer overflow attack patterns targeting WAVLINK devices
Review router logs for repeated failed authentication attempts followed by unexpected behavior
Deploy network monitoring to detect command-and-control communications from router IP addresses

Monitoring Recommendations

Configure network security appliances to inspect and log all traffic to WAVLINK router management interfaces
Implement alerting for any access to the /cgi-bin/login.cgi endpoint from external networks
Monitor for firmware integrity changes on affected devices
Establish baseline behavior profiles for router traffic patterns to identify anomalies

How to Mitigate CVE-2025-5408

Immediate Actions Required

Restrict management interface access to trusted internal networks only using firewall rules
Disable remote administration features if not required for operations
Implement network segmentation to isolate affected routers from critical systems
Monitor affected devices for signs of compromise while awaiting vendor response

Patch Information

At the time of publication, WAVLINK has not responded to disclosure attempts and no official patch is available. Organizations should implement the recommended workarounds and monitor vendor communications for future security updates. The vulnerability affects firmware versions up to V1410_240222. Additional technical details are available through the VulDB Entry #310748.

Workarounds

Configure access control lists (ACLs) to restrict HTTP/HTTPS access to the router management interface from trusted IP addresses only
Place affected devices behind a firewall that blocks external access to port 80/443 on the router
Consider replacing affected devices with alternative router models from vendors with responsive security practices
Implement network intrusion prevention systems (IPS) with signatures for buffer overflow attacks

bash

# Configuration example - Restrict management access using iptables on upstream firewall
# Block external access to WAVLINK router management interface
iptables -A FORWARD -d [WAVLINK_ROUTER_IP] -p tcp --dport 80 -j DROP
iptables -A FORWARD -d [WAVLINK_ROUTER_IP] -p tcp --dport 443 -j DROP

# Allow management access only from trusted admin workstation
iptables -I FORWARD -s [TRUSTED_ADMIN_IP] -d [WAVLINK_ROUTER_IP] -p tcp --dport 80 -j ACCEPT
iptables -I FORWARD -s [TRUSTED_ADMIN_IP] -d [WAVLINK_ROUTER_IP] -p tcp --dport 443 -j ACCEPT