CVE-2023-43239Public exploit

Service crash via flag_5G stack overflow

Published Sep 21, 2023 · Updated Sep 24, 2024

A stack overflow in D-Link DIR-816 A2 1.10CNB05 allows remote attackers to crash its web service with a crafted flag_5G parameter. The showMACfilterMAC handler uses the attacker-controlled parameter string length as maxlen while placing that value in a fixed-size stack buffer. An unauthenticated local-network request can obtain a token from dir_login.asp and send an oversized value that crashes the goahead process; code execution is asserted but not demonstrated.

CVSS severity9.8
Critical
EPSS probability12.24%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

A stack overflow in D-Link DIR-816 A2 1.10CNB05 allows remote attackers to crash its web service with a crafted flag_5G parameter. The showMACfilterMAC handler uses the attacker-controlled parameter string length as maxlen while placing that value in a fixed-size stack buffer. An unauthenticated local-network request can obtain a token from dir_login.asp and send an oversized value that crashes the goahead process; code execution is asserted but not demonstrated.

The record

CVE
CVE-2023-43239
Published
Sep 21, 2023
Updated
Sep 24, 2024
Vendor
D-Link
Product
DIR-816
Classifications
CWE-121, CWE-787, T1499.004
Attack vector
adjacent
Privileges
unauthenticated

Timeline

How it unfolded

  1. Sep 21, 2023CVE publishedPublication date reported by the CVE source.
  2. Sep 24, 2024Record 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 vectoradjacent
Required privilegesunauthenticated

What is affected?

D-Link · DIR-816version=1.10cnb05

Published CVSS scores

8.8CISA-ADPCVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
9.8NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

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.

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No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectoradjacent
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-121Stack-based Buffer Overflow
CWE-787Out-of-bounds Write
T1499.004Application or System Exploitation

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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