CVE-2024-7212: Totolink A7000r Buffer Overflow Vulnerability

CVE-2024-7212 Overview

CVE-2024-7212 is a buffer overflow vulnerability in the TOTOLINK A7000R router running firmware version 9.1.0u.6268_B20220504. The flaw resides in the loginauth function within /cgi-bin/cstecgi.cgi. Attackers can trigger the overflow by manipulating the password argument sent to the endpoint. The vulnerability is remotely exploitable over the network and public exploit details have been disclosed. The vendor was contacted before public disclosure but did not respond. The issue is tracked by VulDB as VDB-272783 and classified under [CWE-120] (Buffer Copy without Checking Size of Input).

Critical Impact
Remote attackers can trigger a buffer overflow in the router's authentication handler, potentially leading to arbitrary code execution or device compromise.

Affected Products

TOTOLINK A7000R router hardware
TOTOLINK A7000R firmware version 9.1.0u.6268_B20220504
Deployments exposing the /cgi-bin/cstecgi.cgi interface to untrusted networks

Discovery Timeline

2024-07-30 - CVE-2024-7212 published to NVD
2026-06-17 - Last updated in NVD database

Technical Details for CVE-2024-7212

Vulnerability Analysis

The vulnerability affects the loginauth function exposed through the CGI endpoint /cgi-bin/cstecgi.cgi. This endpoint handles authentication requests submitted to the router's web management interface. The password parameter passed to loginauth is copied into a fixed-size stack buffer without validating input length. An attacker who supplies an oversized password value overflows the destination buffer and corrupts adjacent memory. Because the router runs the CGI handler with elevated privileges, successful exploitation can allow attackers to hijack execution flow. Exploitation requires only network reachability to the router's management interface and low privileges according to the CVSS 4.0 vector.

Root Cause

The root cause is missing bounds checking when the loginauth function processes the password argument. The code copies attacker-controlled data into a stack buffer using an unsafe string operation, allowing the input to exceed the buffer's allocated size. This maps to [CWE-120], the classic buffer copy without checking size of input.

Attack Vector

An attacker sends a crafted HTTP request to /cgi-bin/cstecgi.cgi targeting the loginauth function with an overlong password parameter. The request can originate from anywhere with network access to the router's web interface. Devices with the management interface exposed to the internet or untrusted LAN segments are directly reachable. Public disclosure of exploitation details is available through the GitHub IoT Vulnerability Documentation and the VulDB #272783 entry.

No verified exploit code is reproduced here. Refer to the linked technical references for parameter-level details.

Detection Methods for CVE-2024-7212

Indicators of Compromise

HTTP POST requests to /cgi-bin/cstecgi.cgi containing abnormally long password field values
Repeated authentication failures or router reboots following requests to loginauth
Outbound connections from the router to unexpected external hosts after suspicious inbound traffic

Detection Strategies

Inspect web server and router logs for requests to /cgi-bin/cstecgi.cgi with password parameter lengths exceeding typical credential sizes
Deploy network intrusion detection signatures that flag oversized POST bodies targeting the loginauth endpoint
Correlate router crash events and unexpected reboots with prior HTTP activity from the same source address

Monitoring Recommendations

Forward router syslog and management interface access logs to a centralized SIEM for retention and analysis
Alert on any external source addresses reaching the router's administrative interface
Baseline normal management traffic patterns to identify anomalous CGI parameter payloads

How to Mitigate CVE-2024-7212

Immediate Actions Required

Restrict access to the router's web management interface to trusted management VLANs only, disabling WAN-side administration
Enforce strong administrative credentials and rotate any credentials that may have traversed a compromised device
Inventory deployed TOTOLINK A7000R devices and identify units running firmware 9.1.0u.6268_B20220504
Consider replacing affected devices if no vendor patch becomes available

Patch Information

No vendor patch has been published in the referenced advisories. The vendor was contacted early about this disclosure but did not respond, per the VulDB submission. Monitor the VulDB entry and TOTOLINK support channels for future firmware updates addressing CVE-2024-7212.

Workarounds

Block inbound traffic to TCP ports hosting the router's web management interface at the network perimeter
Place affected routers behind an upstream firewall that filters requests to /cgi-bin/cstecgi.cgi from untrusted sources
Segment IoT and networking equipment onto isolated VLANs with strict egress filtering to limit post-exploitation movement

bash

# Example: block external access to router management interface via upstream firewall
iptables -A FORWARD -p tcp -d <router_ip> --dport 80 -m iprange ! --src-range <trusted_mgmt_range> -j DROP
iptables -A FORWARD -p tcp -d <router_ip> --dport 443 -m iprange ! --src-range <trusted_mgmt_range> -j DROP