A21 Firmware
CVE-2026-2872
HIGH
Attack ChainAIDerived
Hypothetical attack flow derived from CVE metadata – not a confirmed exploit chain
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AccessAuthenticate to Tenda A21 web interface
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DeliverySend crafted POST to /goform/setBlackRule
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ExploitInject oversized devName parameter
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ExecutionOverflow stack buffer
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ImpactExecute arbitrary code
Vulnerability Assessment
| Weakness |
CWE
OWASP Top 10:2025
A06:2021 - Vulnerable and Outdated Components
ASVS 5.0
V15 - Secure Coding and Architecture Bounds checking, buffer size validation
MITRE ATT&CK
2 techniques across 2 tactics: Execution, Privilege Escalation The technique list with ATT&CK links and the kill-chain view is part of the Basic plan and up. |
| Exploitation Conditions | Tenda A21 firmware version 1.0.0.0 with MAC Filtering Configuration endpoint at /goform/setBlackRule enabled. Attacker requires valid authentication credentials to access the vulnerable endpoint. The devName or mac parameter in the set_device_name function must accept input longer than the allocated stack buffer. |
| Impact | CVSS 8.8 (HIGH). Attack vector: Network. Complexity: Low. Privileges required: Low. User interaction: None. Exploitable via remote/network. Public exploit/POC available. |
| Exploit ScenarioDerived | A remote attacker could exploit this flaw, stack-based buffer overflow. |
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Alert meAnalysisAIv1 – Mar 12, 2026
Stack-based buffer overflow in Tenda A21 1.0.0.0 MAC filtering configuration allows remote authenticated attackers to achieve full system compromise through malicious devName/mac parameters. Public exploit code exists for this vulnerability, which remains unpatched. The flaw affects the set_device_name function in the /goform/setBlackRule endpoint with high exploitability due to network accessibility and low attack complexity.
Earlier versions of this analysis (1)
A security vulnerability has been detected in Tenda A21 1.0.0.0. This vulnerability affects the function set_device_name of the file /goform/setBlackRule of the component MAC Filtering Configuration Endpoint. [CVSS 8.8 HIGH]
RemediationAI
Monitor vendor advisories for a patch. Enable ASLR, DEP/NX, and stack canaries where possible. Restrict network access to the affected service where possible.
Affects your stack
Find out whether the stacks and servers you run are on an affected version.
Checking this CVE against your own stacks and servers is part of the Basic plan and up.
Technical ContextAI · show details
Classified as CWE-119 (Buffer Overflow). Affects A21 Firmware. A security vulnerability has been detected in Tenda A21 1.0.0.0. This vulnerability affects the function set_device_name of the file /goform/setBlackRule of the component MAC Filtering Configuration Endpoint. Such manipulation of the argument devName/mac leads to stack-based buffer overflow. The attack may be performed from remote. The exploit has been disclosed publicly and may be used.
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- Exploit and PoC references, threat intelligence from 22 sources
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Severity by source
AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Primary rating from NVD · only source for this CVE.
CVSS VectorNVD
Lifecycle Timeline
2DescriptionCVE.org
A security vulnerability has been detected in Tenda A21 1.0.0.0. This vulnerability affects the function set_device_name of the file /goform/setBlackRule of the component MAC Filtering Configuration Endpoint. Such manipulation of the argument devName/mac leads to stack-based buffer overflow. The attack may be performed from remote. The exploit has been disclosed publicly and may be used.
Executive ViewAI
Tenda A21 wireless devices are vulnerable to unauthorized MAC filtering configuration changes, potentially allowing attackers to bypass network access controls and gain unauthorized network entry. Organizations using this device model face immediate risk of network infiltration if internet-exposed, requiring urgent mitigation despite the patch being unavailable.
Restrict network access to the /goform/setBlackRule endpoint via firewall rules or WAF; disable remote management interfaces and require local-only configuration access; isolate affected Tenda A21 devices to a separate management VLAN with limited internet exposure; implement network access control (NAC) to monitor for suspicious MAC filtering changes; consider disabling MAC filtering feature if not operationally critical and use alternative access controls.
Threat Intelligence Overview
NVD
CVE.org
EPSS
GitHub
VulDB
How this decision was reached
The engine reads each signal below and applies a fixed list of rules from top to bottom. The first rule that matches sets the recommended action – like a statement, every line is shown.
What every action level means
SSVC AssessmentENISA
Priority Score
Attack Technique
A buffer overflow occurs when a program writes more data to a memory buffer than it was allocated to hold, causing the excess data to spill into adjacent memory regions.
A stack-based buffer overflow occurs when a program writes more data to a buffer located on the stack than it was allocated to hold.
Affected Products (CPE)CVE.org
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Exploit-DB