Cyber Resilience

CVE-2026-4203

Command Injection in Dlink Dnr-202L Firmware ≤ 2026-02-05

Public PoCCommand Injection
Published
16 March 2026
Modified
19 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 0.042 90th percentile
Risk Priority 39 floored blend · peak EPSS

Summary

CVE-2026-4203 is a medium-severity Injection (CWE-74) vulnerability in Dlink Dnr-202L 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 10% 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-2026-4203 is a command injection vulnerability (CWE-74, CWE-77) affecting multiple D-Link NAS devices, including DNS-120, DNR-202L, DNS-315L, DNS-320, DNS-320L, DNS-320LW, DNS-321, DNR-322L, DNS-323, DNS-325, DNS-326, DNS-327L, DNR-326, DNS-340L, DNS-343, DNS-345, DNS-726-4, DNS-1100-4, DNS-1200-05, and DNS-1550-04, up to firmware version 20260205. The flaw exists in the functions cgi_portforwarding_add, cgi_portforwarding_del, cgi_portforwarding_modify, cgi_portforwarding_add_scan, cgi_dhcpd_lease, cgi_ddns, cgi_ip, and cgi_dhcpd within the /cgi-bin/network_mgr.cgi component.

An attacker can exploit this vulnerability remotely over the network with low privileges (PR:L), low attack complexity (AC:L), and no user interaction required. Exploitation enables limited impacts on confidentiality, integrity, and availability (C:L/I:L/A:L), as reflected in its CVSS v3.1 base score of 6.3 (AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:L).

Advisories and technical details are documented in VulDB entries (ctiid.351115, id.351115, submit.770401) and GitHub repositories at https://github.com/wudipjq/my_vuln/blob/main/D-Link8/vuln_122/122.md and https://github.com/wudipjq/my_vuln/blob/main/D-Link8/vuln_123/123.md, which may include mitigation guidance.

The exploit is publicly available, facilitating potential widespread use against vulnerable devices.

OWASP Top 10 for Web (2025)

A05:2025 Injection

EU & UK References

Vulnerability Data

A vulnerability was detected in D-Link DNS-120, DNR-202L, DNS-315L, DNS-320, DNS-320L, DNS-320LW, DNS-321, DNR-322L, DNS-323, DNS-325, DNS-326, DNS-327L, DNR-326, DNS-340L, DNS-343, DNS-345, DNS-726-4, DNS-1100-4, DNS-1200-05 and DNS-1550-04 up to 20260205. Impacted is the function cgi_portforwarding_add/cgi_portforwarding_del/cgi_portforwarding_modify/cgi_portforwarding_add_scan/cgi_dhcpd_lease/cgi_ddns/cgi_ip/cgi_dhcpd of the file /cgi-bin/network_mgr.cgi. The…

more

manipulation results in command injection. The attack may be launched remotely. The exploit is now public and may be used.

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-2026-4205Same product: Dlink Dnr-202L
CVE-2026-4196Same product: Dlink Dnr-202L
CVE-2026-4207Same product: Dlink Dnr-202L
CVE-2026-4195Same product: Dlink Dnr-202L
CVE-2026-4204Same product: Dlink Dnr-202L
CVE-2026-4206Same product: Dlink Dnr-202L
CVE-2026-4210Same product: Dlink Dnr-202L
CVE-2026-4197Same product: Dlink Dnr-202L
CVE-2026-4209Same product: Dlink Dnr-202L
CVE-2024-3273Same product: Dlink Dnr-202L

Affected Assets

dlink
dnr-202l firmware
≤ 2026-02-05
dlink
dnr-326 firmware
≤ 2026-02-05
dlink
dns-1100-4 firmware
≤ 2026-02-05
dlink
dns-120 firmware
≤ 2026-02-05
dlink
dns-1200-05 firmware
≤ 2026-02-05
dlink
dns-1550-04 firmware
≤ 2026-02-05
dlink
dns-315l firmware
≤ 2026-02-05
dlink
dns-320 firmware
≤ 2026-02-05
dlink
dns-320l firmware
≤ 2026-02-05
dlink
dns-320lw firmware
≤ 2026-02-05
+10 more product configuration(s) — see NVD for full list

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