Cyber Resilience

CVE-2025-9935

Command Injection in Totolink N600R Firmware 4.3.0cu.7866_b20220506

Public PoCCommand Injection
Published
04 September 2025
Modified
17 June 2026
Patch / advisory
View advisory
CVSS Score v4 5.5
Click a component to see what it means
Raw vectorCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:L/VA:L/SC:N/SI:N/SA:N/E:P/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
EPSS Score 0.030 86th percentile
Risk Priority 44 floored blend · peak EPSS

Summary

CVE-2025-9935 is a medium-severity Injection (CWE-74) vulnerability in Totolink N600R Firmware. Its CVSS base score is 5.5 (Medium).

Operationally, exploitation aligns with the MITRE ATT&CK technique Command and Scripting Interpreter (T1059); ranked in the top 14% of CVEs by exploit likelihood; it is not currently listed in the CISA KEV catalog; a public proof-of-concept is referenced.

The strongest mitigations our analysis identified map to SA-11 (Developer Testing and Evaluation) and SI-10 (Information Input Validation) — see the control section below for these in your framework.

Deeper analysis AI-assisted summary

Synthesised by an AI model from the NVD description and linked references — a reading aid, not an authoritative source.

CVE-2025-9935 is a command injection vulnerability in the TOTOLINK N600R wireless router running firmware version 4.3.0cu.7866_B20220506. It resides in the function sub_4159F8 within the file /web_cste/cgi-bin/cstecgi.cgi and is tracked under CWE-74 and CWE-77. The flaw permits remote manipulation of inputs that are passed to system commands, rated at CVSS 5.5 with a network attack vector and no required privileges or user interaction.

An unauthenticated attacker can send crafted requests over the network to execute arbitrary commands on the device. Successful exploitation yields limited effects on confidentiality, integrity, and availability of the affected router, with the public exploit code already available for reuse.

Public references document the issue through a detailed proof-of-concept on GitHub along with entries on VulDB, while the vendor site offers no specific mitigation guidance in the supplied references. The associated EPSS score remains low, moving only from 0.0208 to a peak of 0.0273.

OWASP Top 10 for Web (2025)

A05:2025 Injection

EU & UK References

Vulnerability Data

A vulnerability was determined in TOTOLINK N600R 4.3.0cu.7866_B20220506. This vulnerability affects the function sub_4159F8 of the file /web_cste/cgi-bin/cstecgi.cgi. Executing manipulation can lead to command injection. The attack can be executed remotely. The exploit has been publicly disclosed and may be…

more

utilized.

CWE(s)
CWE-74CWE-77

Related Threats

MITRE ATT&CK Enterprise Techniques

T1059 Command and Scripting Interpreter Execution
Adversaries may abuse command and script interpreters to execute commands, scripts, or binaries.
attack.mitre.org →
T1190 Exploit Public-Facing Application Initial Access
Adversaries may attempt to exploit a weakness in an Internet-facing host or system to initially access a network.
attack.mitre.org →
T1221 Template Injection Stealth
Adversaries may create or modify references in user document templates to conceal malicious code or force authentication attempts.
attack.mitre.org →
T1659 Content Injection Initial Access
Adversaries may gain access and continuously communicate with victims by injecting malicious content into systems through online network traffic.
attack.mitre.org →
T1674 Input Injection Execution
Adversaries may simulate keystrokes on a victim’s computer by various means to perform any type of action on behalf of the user, such as launching the command interpreter using keyboard shortcuts, typing an inline script to be executed,…
attack.mitre.org →
T1059.001 PowerShell Execution
Adversaries may abuse PowerShell commands and scripts for execution.
attack.mitre.org →
Derived from this CVE’s CWE(s) via the direct CWE→ATT&CK cross-walk.

CVEs Like This One

CVE-2026-1548Same vendor: Totolink
CVE-2026-1326Same vendor: Totolink
CVE-2026-1601Same vendor: Totolink
CVE-2025-3987Same vendor: Totolink
CVE-2025-5504Same vendor: Totolink
CVE-2025-7615Same vendor: Totolink
CVE-2025-4849Same vendor: Totolink
CVE-2026-5020Same vendor: Totolink
CVE-2026-5105Same vendor: Totolink
CVE-2025-4850Same vendor: Totolink

Affected Assets

totolink
n600r firmware
4.3.0cu.7866_b20220506

Mitigating Controls

Control response

Prevent
Stop it (NIST 800-53)

—

Detect
Catch it (NIST detect / respond)

—

Harden
Shrink the surface (DISA STIG)

—

Validate
Prove the fix (OWASP ASVS)
  • V1.2.1
  • V1.2.3
  • V1.2.5
  • V1.2.8

Mitigating Controls (NIST 800-53 r5) AI

SA-11 Developer Testing and Evaluation good match

Developer testing and evaluation can discover command-construction flaws before deployment.

SI-10 Information Input Validation good match

SI-10 directly requires validation of information inputs to reject malformed or special-element content before it reaches downstream parsers.

SA-8 Security and Privacy Engineering Principles partial match

Secure engineering principles include proper neutralization and safe command construction practices.

Mitigating Controls (NIST CSF 2.0) AI

Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→CSF cross-walk (authority under review) — links open the control.

PR.PS-06 mostly match
prevents

Secure SDLC practices directly require input validation and output encoding that prevent injection flaws.

DE.CM-09 partial match
prevents

Runtime monitoring of software and data can detect anomalous command execution resulting from injection.

ID.RA-01 partial match
prevents

Identifying recorded vulnerabilities enables remediation of command-injection flaws before exploitation.

Mitigating Controls (ISO/IEC 27001:2022 Annex A) AI

Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→ISO cross-walk (authority under review) — links open the control.

A.8.28 Secure coding mostly match
prevents

Secure coding standards require proper escaping and parameterization of commands, directly eliminating CWE-77.

A.8.29 Security testing in development and acceptance mostly match
finds

Security testing in development catches injection vulnerabilities before release.

A.8.15 Logging partial match
finds

Logging supports detection of injection attempts but does not prevent the weakness.

A.8.16 Monitoring activities partial match
finds

Monitoring activities can identify active injection attacks after they occur.

A.8.25 Secure development life cycle partial match
prevents

Secure development life cycle mandates input validation and output encoding that directly prevent injection flaws.

A.8.26 Application security requirements partial match
prevents

Application security requirements explicitly call for controls against injection attacks in software design.

References