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A3600R CVE-2026-5020

| EUVDEUVD-2026-16961 LOW
Command Injection (CWE-77)
2026-03-29 VulDB
2.1
CVSS 4.0 · NVD
View

Vulnerability Assessment

Weakness
CWE
OWASP Top 10:2025
A05:2025 - Injection
ASVS 5.0
V1 - Encoding and Sanitization Command injection prevention
MITRE ATT&CK

1 technique across 1 tactic: Execution

The technique list with ATT&CK links and the kill-chain view is part of the Basic plan and up.

Impact

The vulnerability presents a moderate real-world risk despite its sub-7.0 CVSS score. The CVSS vector indicates attack complexity is low (AC:L) and no user interaction is required (UI:N), with network accessibility (AV:N) but requiring login (PR:L). The publicly available exploit code (POC=YES) significantly elevates practical risk, as threat actors can readily weaponize this without reverse-engineering. The EPSS vector component E:P (Proof of Concept Functional) confirms proof-of-concept exists. However, the authentication requirement (PR:L) limits the attack surface to users with valid credentials - either compromised accounts or administrative access. The moderate CVSS impact (C:L, I:L, A:L) means attackers gain partial confidentiality, integrity, and availability compromise but not complete system takeover. Organizations with Totolik A3600R devices exposed to untrusted networks or shared credentials should prioritize patching, but this is not a critical RCE from the internet perimeter without prior authentication compromise.

Exploit ScenarioDerived

An attacker with valid credentials to the router's web interface (obtained through credential stuffing, phishing, or prior account compromise) sends a specially crafted HTTP request to /cgi-bin/cstecgi.cgi with the setNoticeCfg function and injects shell commands in the NoticeUrl parameter, such as NoticeUrl=http://example.com|whoami or NoticeUrl=$(malicious_command). The router processes this input without sanitization and executes the injected command on the system, potentially allowing the attacker to exfiltrate configuration data, modify firewall rules, create backdoor accounts, or pivot to other network devices. Publicly available exploit code referenced in the VulDB CTI source simplifies weaponization of this attack.

Monitor Track and reassess. Why: LOW severity (CVSS 0.1-3.9).
No patch listed yet 2.9% exploitation probability (EPSS)

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AnalysisAIv1 – Mar 29, 2026

Command injection in Totolink A3600R firmware 4.1.2cu.5182_B20201102 allows authenticated remote attackers to execute arbitrary commands via the NoticeUrl parameter in the setNoticeCfg function of /cgi-bin/cstecgi.cgi. The vulnerability has a CVSS score of 6.3 (low-to-medium severity) but is confirmed by publicly available exploit code, making it an active threat to deployed devices despite the authentication requirement.

RemediationAI

Apply the latest firmware patch released by Totolink for the A3600R model, available at https://www.totolink.net/. If an updated firmware version with a build number later than 5182_B20201102 is available, download and flash it via the router's web interface or management console following Totolink's official upgrade procedures. As an interim mitigation, restrict access to the router's web management interface to trusted IP addresses only using firewall rules or router ACLs, and ensure all administrative accounts use strong, unique passwords to reduce the risk of credential compromise. Additionally, disable remote management features if not actively required.

Affected VersionsENISA

A3600R 4.1.2cu.5182_B20201102

Affected Packages

euvd a3600r no fix

Source: OSV (Open Source Vulnerabilities)

Affects your stack

Affects 1 package in euvd

Checking this CVE against your own stacks and servers is part of the Basic plan and up.

Technical ContextAI · show details

The vulnerability exists in the Parameter Handler component of the Totolink A3600R router's web interface. The setNoticeCfg function fails to properly sanitize user-supplied input in the NoticeUrl parameter before passing it to system command execution, violating CWE-77 (Improper Neutralization of Special Elements used in a Command). The web-accessible CGI script /cgi-bin/cstecgi.cgi processes this parameter without input validation, allowing an authenticated user to inject shell metacharacters and execute arbitrary operating system commands on the router with the privileges of the CGI process.

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  • Exploit and PoC references, threat intelligence from 22 sources

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Severity by source

NVD PRIMARY 2.1 LOW
CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:L/VI:L/VA:L/SC:N/SI:N/SA:N/E:P

Primary rating from NVD · only source for this CVE.

CVSS VectorNVD

Attack Vector
Network
Attack Complexity
Low
Attack Requirements
None
Privileges Required
Low
User Interaction
None
Vulnerable system: Confidentiality
Low
Vulnerable system: Integrity
Low
Vulnerable system: Availability
Low
Subsequent system: Confidentiality
None
Subsequent system: Integrity
None
Subsequent system: Availability
None

Lifecycle Timeline

4
Severity Changed
Apr 29, 2026 - 01:11 NVD
MEDIUM LOW
CVSS changed
Apr 29, 2026 - 01:11 NVD
5.3 (MEDIUM) 2.1 (LOW)
PoC Detected
Mar 30, 2026 - 19:01 vuln.today
Public exploit code
CVE Published
Mar 29, 2026 - 00:30 nvd
MEDIUM 5.3

DescriptionCVE.org

A vulnerability was detected in Totolink A3600R 4.1.2cu.5182_B20201102. Affected by this issue is the function setNoticeCfg of the file /cgi-bin/cstecgi.cgi of the component Parameter Handler. The manipulation of the argument NoticeUrl results in command injection. The attack may be launched remotely. The exploit is now public and may be used.

Executive ViewAI

Why It Matters

Organizations using A vulnerability should be aware of moderate risk from CVE-2026-5020, a command injection vulnerability rated CVSS 5.3. Exploitation could allow attackers to execute code or inject malicious input. Proof-of-concept code is publicly available. Organizations should apply vendor updates when available and monitor for exploitation.

Business Impact: Low
Compensating Controls

Apply vendor patch. If patching is delayed: deploy WAF rules, restrict network access, enable logging.

Threat Intelligence Overview

EPSS Score
2.9%
Top 14% exploitable
Exploit
POC
Public exploit code exists
Data Quality
6 sources
Confidence: High

How this decision was reached

The engine reads each signal below and applies a fixed list of rules from top to bottom. The first rule that matches sets the recommended action – like a statement, every line is shown.

SignalValue
Severity LOW
CISA KEV No
Public POC Yes
EPSS 2.9%
Patch available No
Active threat No
Deciding rule
LOW severity (CVSS 0.1-3.9)
What every action level means
Emergency Immediate action required. Criteria: CRITICAL + in CISA KEV (actively exploited) without patch, OR CRITICAL + EPSS > 30% without patch, OR CRITICAL + active threat signals without patch.
Act Now Prioritize within 24-48h. Criteria: in KEV with patch available, OR CRITICAL + public POC, OR HIGH + EPSS > 10%, OR CRITICAL + active threat, OR any CRITICAL severity.
This Week Schedule remediation this week. Criteria: HIGH severity (CVSS 7.0-8.9). Patch within normal change window.
This Month Plan within 30 days. Criteria: MEDIUM severity (CVSS 4.0-6.9), lower exploitation probability. Include in regular patch cycle.
Monitor Track and reassess. Criteria: LOW severity (CVSS 0.1-3.9), minimal exploitation risk. No immediate action needed.

SSVC AssessmentENISA

SSVC Decision
Scheduled
Exploitation
Poc
System Exposure· derived
Open
Automatable
No
Human Impact
Low
Technical Impact
Partial

Priority Score

33
Low Medium High Critical
KEV: 0
EPSS: +3
CVSS: +10
PoC: +20
Weaponized: 0
Threat intel: 0
Gov advisory: 0

Attack Technique

OS command injection occurs when an application passes unsanitized user input directly into system shell commands.

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