Cyber Resilience

CVE-2026-5101

Command Injection in Totolink A3300R Firmware 17.0.0cu.557_b20221024

Public PoCCommand Injection
Published
29 March 2026
Modified
30 March 2026
Patch / advisory
View advisory
CVSS Score v4 5.3
Click a component to see what it means
Raw vectorCVSS: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/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 0.022 81th percentile
Risk Priority 38 floored blend · peak EPSS

Summary

CVE-2026-5101 is a medium-severity Injection (CWE-74) vulnerability in Totolink A3300R Firmware. Its CVSS base score is 5.3 (Medium).

Operationally, exploitation aligns with the MITRE ATT&CK technique Command and Scripting Interpreter (T1059); ranked in the top 19% 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-2026-5101 is a command injection vulnerability affecting the Totolink A3300R router on firmware version 17.0.0cu.557_b20221024. The issue resides in the setLanCfg function of the /cgi-bin/cstecgi.cgi file within the Parameter Handler component, where manipulation of the lanIp argument triggers command injection. Published on 2026-03-29, it is associated with CWEs-74, CWE-77, and CWE-78, and carries a CVSS v3.1 base score of 6.3 (AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:L).

Remote attackers with low privileges can exploit this vulnerability over the network with low complexity and no user interaction required. Exploitation enables arbitrary command execution, potentially leading to low impacts on confidentiality, integrity, and availability, such as limited data access, modification, or disruption on the affected device. A public exploit is available, increasing the risk of widespread use.

Advisories referenced in VULDB entries (vuln/354126 and related CTI) document the vulnerability details and submission, while a GitHub repository provides exploit code and a README. The Totolink vendor website is listed for potential firmware updates or mitigation guidance. Security practitioners should verify patches directly from these sources.

OWASP Top 10 for Web (2025)

A05:2025 Injection

EU & UK References

Vulnerability Data

A vulnerability was identified in Totolink A3300R 17.0.0cu.557_b20221024. This affects the function setLanCfg of the file /cgi-bin/cstecgi.cgi of the component Parameter Handler. The manipulation of the argument lanIp leads to command injection. Remote exploitation of the attack is possible. The…

more

exploit is publicly available and might be used.

CWE(s)
CWE-74CWE-77CWE-78

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 →
T1059.003 Windows Command Shell Execution
Adversaries may abuse the Windows command shell for execution.
attack.mitre.org →
T1059.004 Unix Shell Execution
Adversaries may abuse Unix shell commands and scripts for execution.
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 →
Derived from this CVE’s CWE(s) via the direct CWE→ATT&CK cross-walk.

CVEs Like This One

CVE-2026-5105Same product: Totolink A3300R
CVE-2026-5176Same product: Totolink A3300R
CVE-2026-5177Same product: Totolink A3300R
CVE-2026-5178Same product: Totolink A3300R
CVE-2026-5102Same product: Totolink A3300R
CVE-2026-5104Same product: Totolink A3300R
CVE-2026-5103Same product: Totolink A3300R
CVE-2026-31172Same product: Totolink A3300R
CVE-2025-55901Same product: Totolink A3300R
CVE-2026-31167Same product: Totolink A3300R

Affected Assets

totolink
a3300r firmware
17.0.0cu.557_b20221024

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.

AC-6 Least Privilege partial match

Least privilege reduces the permissions available to any process that could be subverted by injected commands.

CM-7 Least Functionality partial match

Least functionality restricts available OS commands and interpreters, limiting the blast radius of injection.

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.

PR.PS-02 partial match
prevents

Routine patching/maintenance can remediate known command-injection CVEs in dependencies (partial forward) but does nothing to stop developers from introducing improper neutralization in custom code (none reverse).

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