CyberSecBulletin
CVE-2026-4209NVD status: Analyzed

DNS-120: Improper Neutralization of Special Elements used in a Command

Published Updated By the CyberSecBulletin desk

CVE-2026-4209 is a critical-severity improper neutralization of special elements used in a command vulnerability in DNS-120 from D-Link, with a CVSS 3.1 base score of 9.8 out of 10. It can be exploited remotely over the network by an unauthenticated attacker, without any action from a user. Affected DNS-120 versions: 20260205. The record does not name a fixed version, so check the vendor advisory. There is no confirmed exploitation so far. EPSS estimates a 7.65% chance of exploitation within 30 days, which is in the top 5.33% of all scored CVEs.

Patch this week

Critical severity: a successful attack would have severe impact.

What to do

  1. Check which version of DNS-120 you run against the affected versions below, and install the vendor's latest release.
  2. Until you can update, restrict network access to the affected service so it is not reachable from untrusted networks.

Affected products and versions

VendorProductAffected versionsFixed in
D-LinkDNS-12020260205Not stated
D-LinkDNR-202L20260205Not stated
D-LinkDNS-315L20260205Not stated
D-LinkDNS-32020260205Not stated
D-LinkDNS-320L20260205Not stated
D-LinkDNS-320LW20260205Not stated
D-LinkDNS-32120260205Not stated
D-LinkDNR-322L20260205Not stated
D-LinkDNS-32320260205Not stated
D-LinkDNS-32520260205Not stated
D-LinkDNS-32620260205Not stated
D-LinkDNS-327L20260205Not stated
D-LinkDNR-32620260205Not stated
D-LinkDNS-340L20260205Not stated
D-LinkDNS-34320260205Not stated
D-LinkDNS-34520260205Not stated
D-LinkDNS-726-420260205Not stated
D-LinkDNS-1100-420260205Not stated
D-LinkDNS-1200-0520260205Not stated
D-LinkDNS-1550-0420260205Not stated
D-LinkDnr-202l Firmware2026-02-05 and earlierNot stated
D-LinkDnr-326 Firmware2026-02-05 and earlierNot stated
D-LinkDns-1100-4 Firmware2026-02-05 and earlierNot stated
D-LinkDns-120 Firmware2026-02-05 and earlierNot stated
D-LinkDns-1200-05 Firmware2026-02-05 and earlierNot stated

Version data comes from the organisation that assigned the CVE; 15 further products are omitted here. Confirm against the vendor advisory before deciding you are unaffected.

How the severity score breaks down

Attack vector
NetworkCan be exploited remotely over a network, including the internet.
Attack complexity
LowNo special conditions are needed; the attack works reliably.
Privileges required
NoneNo account or login is needed.
User interaction
NoneNo action by a victim is required.
Scope
UnchangedImpact stays within the vulnerable component.
Confidentiality
HighAll data handled by the component can be read.
Integrity
HighData or code can be modified at will.
Availability
HighThe component can be taken down completely.

Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H. Scored by NVD.

Scoring systemScoreSeverityScored by
CVSS 4.02.1LowCNA (vuldb.com)
CVSS 3.16.3MediumCNA (vuldb.com)
CVSS 3.19.8CriticalNVD
CVSS 2.06.5MediumCNA (vuldb.com)

Official description

A vulnerability was identified 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. Affected is the function cgi_create_import_users/cgi_user_batch_create/cgi_user_set_quota/cgi_user_del/cgi_user_modify/cgi_group_set_quota/cgi_group_modify/cgi_group_add/cgi_user_add/cgi_get_modify_group_info/cgi_chg_admin_pw of the file /cgi-bin/account_mgr.cgi. The manipulation leads to command injection. It is possible to initiate the attack remotely. The exploit is publicly available and might be used.

Source: the CVE record as published by its numbering authority, via NVD and CVE.org.

The underlying weakness: Improper Neutralization of Special Elements used in a Command

The product constructs all or part of a command using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify the intended command when it is sent to a downstream component.

How developers prevent this class of flaw

  • If at all possible, use library calls rather than external processes to recreate the desired functionality.
  • If possible, ensure that all external commands called from the program are statically created.
  • Run time: Run time policy enforcement may be used in an allowlist fashion to prevent use of any non-sanctioned commands.

More Improper Neutralization of Special Elements used in a Command vulnerabilities (CWE-77)

Timeline

  1. CVE record published.
  2. CISA published its SSVC assessment (exploitation: poc, automatable: no, technical impact: partial).
  3. Record last changed materially (score, affected products, status or references).

References

Third-party and government advisories

Technical write-ups (may include proof of concept)

Other references

Other vulnerabilities in DNS-120

All DNS-120 vulnerabilities

Recent Improper Neutralization of Special Elements used in a Command vulnerabilities

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