CyberSecBulletin
CVE-2026-5212NVD status: Analyzed

DNS-120: Out-of-bounds Write

Published Updated By the CyberSecBulletin desk

CVE-2026-5212 is a high-severity out-of-bounds write vulnerability in DNS-120 from D-Link, with a CVSS 3.1 base score of 8.8 out of 10. It can be exploited remotely over the network by an attacker with a low-privileged account, 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 0.75% chance of exploitation within 30 days, higher than 56% of scored CVEs.

Next patch cycle

High severity with no evidence of exploitation so far.

What to do

  1. Check which version of DNS-120 you run against the affected versions below, and install the vendor's latest release.

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
LowA basic user account is enough.
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:L/UI:N/S:U/C:H/I:H/A:H. Scored by CNA (vuldb.com).

Scoring systemScoreSeverityScored by
CVSS 4.07.4HighCNA (vuldb.com)
CVSS 3.18.8HighCNA (vuldb.com)
CVSS 2.09.0HighCNA (vuldb.com)

Official description

A vulnerability has been found 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. This issue affects the function Webdav_Upload_File of the file /cgi-bin/webdav_mgr.cgi. The manipulation of the argument f_file leads to stack-based buffer overflow. The attack is possible to be carried out remotely. The exploit has been disclosed to the public and may be used.

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

The underlying weakness: Out-of-bounds Write

The product writes data past the end, or before the beginning, of the intended buffer.

How developers prevent this class of flaw

  • Use a language that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid. For example, many languages that perform their own memory management, such as Java and Perl, are not subject to buffer overflows. Other languages, such as Ada and C#, typically provide overflow protection, but the protection can be disabled by the programmer. Be wary that a language's interface to native code may still be subject to overflows, even if the language itself is theoretically safe.
  • Use a vetted library or framework that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid. Examples include the Safe C String Library (SafeStr) by Messier and Viega, and the Strsafe.h library from Microsoft. These libraries provide safer versions of overflow-prone string-handling functions.
  • Use automatic buffer overflow detection mechanisms that are offered by certain compilers or compiler extensions. Examples include: the Microsoft Visual Studio /GS flag, Fedora/Red Hat FORTIFY_SOURCE GCC flag, StackGuard, and ProPolice, which provide various mechanisms including canary-based detection and range/index checking. D3-SFCV (Stack Frame Canary Validation) from D3FEND discusses canary-based detection in detail.

More Out-of-bounds Write vulnerabilities (CWE-787)

Timeline

  1. CVE record published.
  2. CISA published its SSVC assessment (exploitation: poc, automatable: no, technical impact: total).
  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 Out-of-bounds Write vulnerabilities

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