CVE-2026-4211: A weakness has been identified in D-Link DNS-120, DNR-202L, DNS-315L, DNS-320, DNS-320L, DNS-320LW, DNS-321, D
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This month
HIGH 8.8UPGRADEUPGRADEUPGRADE
CVE-2026-4211 is a high-severity flaw (CVSS 8.8) affecting dnr-202l firmware, dnr-326 firmware, dns-1100-4 firmware. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.
A weakness has been 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 by this issue is the function Local_Backup_Info of the file /cgi-bin/local_backup_mgr.cgi. This manipulation of the argument f_idx causes stack-based buffer overflow. The attack can
Last updated 2026-06-17 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score
Am I affected?
Timeline
Published CVE record published
Updated Record last modified
dlink dnr-202l firmware UPGRADE
Affected: <= 2026-02-05
Fixed in: newer than 2026-02-05
Safe to downgrade to: no unaffected older release
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.
dlink dnr-326 firmware UPGRADE
Affected: <= 2026-02-05
Fixed in: newer than 2026-02-05
Safe to downgrade to: no unaffected older release
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.
dlink dns-1100-4 firmware UPGRADE
Affected: <= 2026-02-05
Fixed in: newer than 2026-02-05
Safe to downgrade to: no unaffected older release
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.
dlink dns-120 firmware UPGRADE
Affected: <= 2026-02-05
Fixed in: newer than 2026-02-05
Safe to downgrade to: no unaffected older release
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.
dlink dns-1200-05 firmware UPGRADE
Affected: <= 2026-02-05
Fixed in: newer than 2026-02-05
Safe to downgrade to: no unaffected older release
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.
dlink dns-1550-04 firmware UPGRADE
Affected: <= 2026-02-05
Fixed in: newer than 2026-02-05
Safe to downgrade to: no unaffected older release
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.
Verify at the official sourceNVD · 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-2026-4211?
dnr-202l firmware: upgrade to newer than 2026-02-05; dnr-326 firmware: upgrade to newer than 2026-02-05; dns-1100-4 firmware: upgrade to newer than 2026-02-05. Exact commands for each OS are on this page.
Is CVE-2026-4211 being exploited?
CVE-2026-4211 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-2026-4211 affect?
CVE-2026-4211 affects dnr-202l firmware, dnr-326 firmware, dns-1100-4 firmware. Severity is high (CVSS 8.8). A weakness has been 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
How urgent is CVE-2026-4211?
Priority 50/100. High severity; Public exploit reference
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