CVE-2023-43239: D-Link DIR-816 A2 v1.10CNB05 was discovered to contain a stack overflow via parameter flag_5G in showMACfilter

This week

CRITICAL 9.8REMOTEMITIGATE

CVE-2023-43239 is a critical-severity flaw (CVSS 9.8) affecting dir-816 a2 firmware. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

D-Link DIR-816 A2 v1.10CNB05 was discovered to contain a stack overflow via parameter flag_5G in showMACfilterMAC.

Why this priority

Critical severity
EPSS top 4%: very likely to be exploited
Public exploit reference
Remotely exploitable, no login, no user action

A fixed release or distro patch exists.

Risk facts

CVSS score	9.8 (Critical)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	13.3% (top 4%)
CISA exploited list	No
Weakness	CWE-787, CWE-121
Published	2023-09-21
Last modified	2026-06-17

Publisher (CNA): MITRE · Vendor: dlink

Last updated 2026-06-17 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2023-09-21 13:15 UTCPublished CVE record published
2026-06-17 06:25 UTCUpdated Record last modified

dlink dir-816 a2 firmware MITIGATE

Affected: 1.10cnb05

Fixed in: no fixed release known

Safe to downgrade to: a release before 1.10cnb05

Check your OS release

cat /etc/os-release; uname -r

Debian / Ubuntu

sudo apt update && sudo apt full-upgrade

RHEL / Amazon Linux / Fedora

sudo dnf upgrade --refresh

Windows

Install the latest cumulative update from Windows Update

If no patch exists yet

OS downgrades are not safe. Apply the vendor mitigation from the advisory and restrict exposure.

Exact fixes by distribution

A distro patch exists: prefer upgrading over downgrading.

Fedora ELN · libmamba · FIXED · 2.10.0-1.eln159 · FEDORA-2026-cc57be9e65 · source

sudo dnf upgrade --advisory=FEDORA-2026-cc57be9e65

Fedora 46 · rubygem-selenium-webdriver · FIXED · 4.34.0-5.fc46 · FEDORA-2026-111c6e6363 · source

sudo dnf upgrade --advisory=FEDORA-2026-111c6e6363

Public exploits and detection

Public code exists for this CVE. Treat unpatched systems as at risk, and only run PoCs in a lab.

Write-up: github.com/peris-navince/founded-0-days/blob/main/Dlink/816/showMACfilterMAC/1.md
Write-up: www.dlink.com/en/security-bulletin/

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2023-43239?

dir-816 a2 firmware: mitigate or apply the listed mitigation. Exact commands for each OS are on this page.

Is CVE-2023-43239 being exploited?

CVE-2023-43239 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2023-43239 affect?

CVE-2023-43239 affects dir-816 a2 firmware. Severity is critical (CVSS 9.8). D-Link DIR-816 A2 v1.10CNB05 was discovered to contain a stack overflow via parameter flag_5G in showMACfilterMAC.

How urgent is CVE-2023-43239?

Priority 68/100. Critical severity; EPSS top 4%: very likely to be exploited; Public exploit reference; Remotely exploitable, no login, no user action

Software pages

D-Link vulnerabilities

Related CVEs

CVE-2025-44835 MEDIUM 6.3 MITIGATE D-Link DIR-816 A2V1.1.0B05 was found to contain a command injection in iptablesWebsFilterRun, which allows rem
CVE-2024-0921 MEDIUM 4.7 MITIGATE A vulnerability has been found in D-Link DIR-816 A2 1.10CNB04 and classified as critical
CVE-2023-43240 CRITICAL 9.8 MITIGATE D-Link DIR-816 A2 v1.10CNB05 was discovered to contain a stack overflow via parameter sip_address in ipportFil
CVE-2023-43238 CRITICAL 9.8 MITIGATE D-Link DIR-816 A2 v1.10CNB05 was discovered to contain a stack overflow via parameter nvmacaddr in form2Dhcpip
CVE-2023-43237 CRITICAL 9.8 MITIGATE D-Link DIR-816 A2 v1.10CNB05 was discovered to contain a stack overflow via parameter macCloneMac in setMAC.

References

← Back to latest CVEs