CVE-2026-4565: A vulnerability was detected in Tenda AC21 16.03.08.16

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HIGH 8.8MITIGATE

CVE-2026-4565 is a high-severity flaw (CVSS 8.8) affecting ac21 firmware. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

A vulnerability was detected in Tenda AC21 16.03.08.16. Impacted is the function formSetQosBand of the file /goform/SetNetControlList. Performing a manipulation of the argument list results in buffer overflow. The attack can be initiated remotely. The exploit is now public and may be used.

Why this priority

High severity
Public exploit reference

No fix is published yet: follow the downgrade or mitigation steps.

Risk facts

CVSS score	8.8 (High)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	Low
User interaction	None
EPSS exploit chance	1.0% (top 39%)
CISA exploited list	No
Weakness	CWE-119, CWE-120
Published	2026-03-23
Last modified	2026-06-17

Publisher (CNA): VulDB · Vendor: tenda

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

Am I affected?

Timeline

2026-03-23 01:16 UTCPublished CVE record published
2026-06-17 10:56 UTCUpdated Record last modified

tenda ac21 firmware MITIGATE

Affected: 16.03.08.16

Fixed in: no fixed release known

Safe to downgrade to: a release before 16.03.08.16

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 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-2026-4565?

ac21 firmware: mitigate or apply the listed mitigation. Exact commands for each OS are on this page.

Is CVE-2026-4565 being exploited?

CVE-2026-4565 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-2026-4565 affect?

CVE-2026-4565 affects ac21 firmware. Severity is high (CVSS 8.8). A vulnerability was detected in Tenda AC21 16.03.08.16. Impacted is the function formSetQosBand of the file /goform/SetNetControlList. Performing a manipulation of the argument list results in buffer overflow. The attack can be initiated re

How urgent is CVE-2026-4565?

Priority 51/100. High severity; Public exploit reference

References

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