CVE-2026-4181Public exploitNetwork attack vector

Unauthenticated code execution via unchecked form copy

Published Mar 15, 2026 · Updated Mar 15, 2026

Stack-based buffer overflow in D-Link DIR-816 1.10CNB05 allows remote attackers to execute code through crafted repeater form data. The goahead form2RepeaterStep2.cgi handler copies oversized key1, key2, key3, key4, or pskValue data into a stack-local buffer without length validation, overwriting its return address. The endpoint is reachable without authentication; the published request demonstrates a persistent router crash, while code execution is reported from return-address control.

CVSS severity9.8
Critical
EPSS probability1.18%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Stack-based buffer overflow in D-Link DIR-816 1.10CNB05 allows remote attackers to execute code through crafted repeater form data. The goahead form2RepeaterStep2.cgi handler copies oversized key1, key2, key3, key4, or pskValue data into a stack-local buffer without length validation, overwriting its return address. The endpoint is reachable without authentication; the published request demonstrates a persistent router crash, while code execution is reported from return-address control.

The record

CVE
CVE-2026-4181
Published
Mar 15, 2026
Updated
Mar 15, 2026
Vendor
D-Link
Product
DIR-816
Classifications
CWE-119, CWE-787, CWE-121, T1499
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Mar 15, 2026CVE publishedPublication date reported by the CVE source.
  2. Mar 15, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=1.10CNB05

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

D-Link · DIR-816version=1.10CNB05

Published CVSS scores

9.8VulDBCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
10.0VulDBAV:N/AC:L/Au:N/C:C/I:C/A:C
8.9VulDBCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:P

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-119Improper Restriction of Operations within the Bounds of a Memory Buffer
CWE-787Out-of-bounds Write
CWE-121Stack-based Buffer Overflow
T1499Endpoint Denial of Service

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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