Totolink NR1800X Command Injection (CVE-2026-7548) Publicly Exploitable
The National Vulnerability Database (NVD) has detailed CVE-2026-7548, a high-severity command injection flaw impacting Totolink NR1800X routers running firmware version 9.1.0u.6279_B20210910. This vulnerability resides within the sub_41A68C function of /cgi-bin/cstecgi.cgi, specifically triggered by manipulating the setUssd argument.
This is a critical issue. The attack can be executed remotely, and an exploit has already been made public. Attackers can leverage this to gain arbitrary command execution on affected devices, leading to full system compromise. The CVSSv3.1 score of 8.8 (High) reflects the network-based attack vector, low privileges required, and complete impact on confidentiality, integrity, and availability.
For defenders, this means exposed Totolink NR1800X devices are low-hanging fruit. The public exploit significantly lowers the bar for attackers, from opportunistic scanning to targeted network infiltration. Expect this to be rapidly integrated into botnets and initial access brokers’ toolkits.
What This Means For You
- If your organization or remote employees use Totolink NR1800X routers, immediately identify devices running firmware version 9.1.0u.6279_B20210910. Isolate these devices from critical networks, or better yet, replace them if no patch is available. Assume compromise if you cannot confirm they were offline or patched before the exploit became public.
Related ATT&CK Techniques
🛡️ Detection Rules
3 rules · 6 SIEM formats3 detection rules auto-generated for this incident, mapped to MITRE ATT&CK. Sigma YAML is free — export to any SIEM format via the Intel Bot.
CVE-2026-7548 Totolink NR1800X Command Injection via setUssd
title: CVE-2026-7548 Totolink NR1800X Command Injection via setUssd
id: scw-2026-05-01-ai-1
status: experimental
level: critical
description: |
Detects attempts to exploit CVE-2026-7548 in Totolink NR1800X routers. The vulnerability allows command injection through the setUssd parameter in cstecgi.cgi. This rule specifically looks for the '/cgi-bin/cstecgi.cgi' path combined with the 'setUssd=' parameter, and common command injection indicators like 'ping -c 127.0.0.1' which are often used in exploit payloads to test for successful command execution.
author: SCW Feed Engine (AI-generated)
date: 2026-05-01
references:
- https://shimiscyberworld.com/posts/nvd-CVE-2026-7548/
tags:
- attack.initial_access
- attack.t1190
logsource:
category: webserver
detection:
selection:
cs-uri|contains:
- '/cgi-bin/cstecgi.cgi'
cs-uri-query|contains:
- 'setUssd='
cs-uri-query|contains:
- 'ping'
cs-uri-query|contains:
- '-c'
cs-uri-query|contains:
- '127.0.0.1'
condition: selection
falsepositives:
- Legitimate administrative activity
Source: Shimi's Cyber World · License & reuse
Indicators of Compromise
| ID | Type | Indicator |
|---|---|---|
| CVE-2026-7548 | Command Injection | Totolink NR1800X version 9.1.0u.6279_B20210910 |
| CVE-2026-7548 | Command Injection | Vulnerable file: /cgi-bin/cstecgi.cgi |
| CVE-2026-7548 | Command Injection | Vulnerable function: sub_41A68C |
| CVE-2026-7548 | Command Injection | Vulnerable argument: setUssd |
Written by SCW Vulnerability Desk
Source & Attribution
| Source Platform | NVD |
| Channel | National Vulnerability Database |
| Published | May 01, 2026 at 06:16 UTC |
This content was AI-rewritten and enriched by Shimi's Cyber World based on the original source. All intellectual property rights remain with the original author.
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