Which versions of Tenda are affected by CVE-2026-4565?

A high-severity vulnerability in Tenda AC21 routers allows authenticated attackers to remotely compromise system integrity, steal data, or cause service disruption.. A patch is available.

Is there a public PoC exploit available for CVE-2026-4565?

Yes, a public proof-of-concept exploit is available for CVE-2026-4565. Prioritise patching immediately. EPSS: 0.1%.

How to fix or mitigate CVE-2026-4565?

Within 24 hours: Identify and inventory all Tenda AC21 routers running firmware 16.03.08.16 in your environment; verify network segmentation restricts router management access to authorized personnel only. Within 7 days: Disable remote management features on affected routers if operationally feasible; restrict administrative access to the /goform/SetNetControlList endpoint to trusted internal networks only using firewall rules. Within 30 days: Contact Tenda for patch ETA and evaluate replacement with routers from vendors with active security support; test and deploy any available firmware updates immediately upon release.

Tenda CVE-2026-4565

Q: What is the CVSS score of CVE-2026-4565?

CVE-2026-4565 has a CVSS 4.0 base score of 7.4 (High). CVSS vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:P/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X. EPSS exploitation probability: 0.1%.

EUVD-2026-14343 HIGH

Classic Buffer Overflow (CWE-120)

2026-03-23 VulDB

Buffer Overflow Tenda

7.4

CVSS 4.0 · NVD

Severity by source

NVD PRIMARY

7.4 HIGH

CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:P/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

Primary rating from NVD · only source for this CVE.

CVSS VectorNVD

CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:P/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

Attack Vector

Network

Attack Complexity

Low

Privileges Required

Low

User Interaction

None

Scope

Lifecycle Timeline

PoC Detected

Apr 03, 2026 - 11:31 vuln.today

Public exploit code

Patch released

Mar 31, 2026 - 21:13 nvd

Patch available

EUVD ID Assigned

Mar 23, 2026 - 01:00 euvd

EUVD-2026-14343

Analysis Generated

Mar 23, 2026 - 01:00 vuln.today

CVE Published

Mar 23, 2026 - 00:34 nvd

HIGH 7.4

DescriptionCVE.org

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.

AnalysisAI

Buffer overflow in Tenda AC21 firmware version 16.03.08.16 allows authenticated remote attackers to achieve complete system compromise through crafted QoS configuration requests to the SetNetControlList endpoint. Public exploit code exists for this vulnerability, and no patch is currently available. An attacker with valid credentials can execute arbitrary code with full system privileges (confidentiality, integrity, and availability impact).

Technical ContextAI

This vulnerability affects the Tenda AC21 wireless router (cpe:2.3:a:tenda:ac21:*:*:*:*:*:*:*:*) in its QoS bandwidth management functionality. The root cause is classified as CWE-120 (Buffer Copy without Checking Size of Input), commonly known as a classic buffer overflow. The formSetQosBand function in the /goform/SetNetControlList endpoint fails to properly validate the size of user-supplied input in the 'list' parameter before copying it to a fixed-size buffer. This allows an attacker to write beyond the allocated memory boundary, potentially overwriting adjacent memory regions including return addresses, function pointers, or other critical data structures. In embedded router firmware, such vulnerabilities often arise from unsafe C functions like strcpy, sprintf, or gets that do not perform bounds checking.

RemediationAI

Check the Tenda vendor website at https://www.tenda.com.cn/ for updated firmware releases that address this buffer overflow vulnerability and upgrade immediately if available. As of the current intelligence, no official patch or remediation timeline (RL:X) has been published by Tenda. Until an official patch is deployed, implement network-level mitigations including restricting administrative access to the router's web interface to trusted IP addresses only, ensuring strong non-default administrative credentials are in place, disabling remote management features if not required, and placing affected devices behind additional network segmentation or firewall rules. Organizations should consider replacing affected devices with alternative models if Tenda fails to release timely security updates. Monitor VulDB entry https://vuldb.com/?id.352402 for updates on vendor response.