What is the CVSS score of CVE-2026-2871?

CVE-2026-2871 has a CVSS 3.1 base score of 8.8 (High). CVSS vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H. EPSS exploitation probability: 0.0%.

Is there a public PoC exploit available for CVE-2026-2871?

Yes, a public proof-of-concept exploit is available for CVE-2026-2871. Prioritise patching immediately. EPSS: 0.0%.

How to fix or mitigate CVE-2026-2871?

Within 24 hours: Inventory all Tenda A21 1.0.0.0 devices in production and isolate affected units from critical networks if possible; enable all available logging and monitoring. Within 7 days: Implement network segmentation to restrict administrative access to these devices and deploy WAF rules blocking /goform/SetIpMacBind requests from untrusted sources. Within 30 days: Replace affected Tenda A21 devices with patched alternatives or equipment from vendors with active security support; document all instances and maintain audit trail of affected networks.

DNS CVE-2026-2871

HIGH

Buffer Overflow (CWE-119)

2026-02-21 cna@vuldb.com

Buffer Overflow DNS Stack Overflow Tenda A21 Firmware

8.8

CVSS 3.1 · NVD

View

Attack ChainAIDerived

Hypothetical attack flow derived from CVE metadata – not a confirmed exploit chain

Access

Authenticate to Tenda A21 web interface
Exploit

Send crafted POST request to /goform/SetIpMacBind
Execution

Overflow stack buffer in fromSetIpMacBind function
Impact

Execute arbitrary code with device privileges

Vulnerability Assessment

Weakness	CWE CWE-119 OWASP Top 10:2025 A06:2021 - Vulnerable and Outdated Components ASVS 5.0 V15 - Secure Coding and Architecture Bounds checking, buffer size validation MITRE ATT&CK 2 techniques across 2 tactics: Execution,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. Sign in to read
Exploitation Conditions	Tenda A21 firmware version 1.0.0.0; requires valid login credentials to access /goform/SetIpMacBind endpoint; web interface must be accessible on default HTTP port 80 or HTTPS port 443
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 vulnerability to compromise the affected system.

This Week Schedule remediation this week. Why: HIGH severity (CVSS 7.0-8.9).

No patch listed yet 0.0% exploitation probability (EPSS)

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AnalysisAIv1 – Mar 12, 2026

Remote code execution in Tenda A21 1.0.0.0 firmware results from a stack buffer overflow in the SetIpMacBind function accessible via the /goform/SetIpMacBind endpoint, allowing unauthenticated remote attackers to execute arbitrary code with high integrity and availability impact. Public exploit code exists for this vulnerability, and no patch is currently available, creating significant risk for affected devices.

Earlier versions of this analysis (1)

v1 Mar 12, 2026 - 22:04 CVSS 8.8

A weakness has been identified in Tenda A21 1.0.0.0. This affects the function fromSetIpMacBind of the file /goform/SetIpMacBind. [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 weakness has been identified in Tenda A21 1.0.0.0. This affects the function fromSetIpMacBind of the file /goform/SetIpMacBind. This manipulation of the argument list causes stack-based buffer overflow. The attack is possible to be carried out remotely. The exploit has been made available to the public and could be used for attacks.

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Exploit and PoC references, threat intelligence from 22 sources

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Severity by source

NVD PRIMARY 8.8 HIGH

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

Attack Vector

Network

Attack Complexity

Low

Privileges Required

Low

User Interaction

None

Scope

Unchanged

Confidentiality

High

Integrity

High

Availability

High

Lifecycle Timeline

PoC Detected

Feb 23, 2026 - 20:59 vuln.today

Public exploit code

CVE Published

Feb 21, 2026 - 16:16 nvd

HIGH 8.8

DescriptionCVE.org

A weakness has been identified in Tenda A21 1.0.0.0. This affects the function fromSetIpMacBind of the file /goform/SetIpMacBind. This manipulation of the argument list causes stack-based buffer overflow. The attack is possible to be carried out remotely. The exploit has been made available to the public and could be used for attacks.

Executive ViewAI

Why It Matters

A high-severity vulnerability in Tenda A21 wireless routers (CVE-2026-2871) allows unauthenticated attackers to compromise network devices through the IP-MAC binding function. Organizations using this equipment face immediate risk of unauthorized network access, data interception, and lateral movement into corporate systems, particularly affecting remote offices and branch locations.

Business Impact: High

Compensating Controls

Implement network access control lists (ACLs) restricting access to /goform/SetIpMacBind endpoint; disable IP-MAC binding feature if operationally feasible; deploy Web Application Firewall (WAF) rules to monitor and block suspicious requests to the vulnerable function; place affected routers behind additional security appliances; implement strict network segmentation isolating these devices from sensitive systems; enable enhanced monitoring and alerting for administrative access attempts.

Threat Intelligence Overview

EPSS Score

0.0%

Top 91% exploitable

Exploit

POC

Public exploit code exists

Data Quality

5 sources

Confidence: Medium

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.

SignalValue

Severity HIGH

CISA KEV No

Public POC Yes

EPSS 0.0%

Patch available No

Active threat No

Deciding rule

HIGH severity (CVSS 7.0-8.9)

What every action level means

Emergency Immediate action required. Criteria: CRITICAL + in CISA KEV (actively exploited) without patch, OR CRITICAL + EPSS > 30% without patch, OR CRITICAL + active threat signals without patch.

Act Now Prioritize within 24-48h. Criteria: in KEV with patch available, OR CRITICAL + public POC, OR HIGH + EPSS > 10%, OR CRITICAL + active threat, OR any CRITICAL severity.

This Week Schedule remediation this week. Criteria: HIGH severity (CVSS 7.0-8.9). Patch within normal change window.

This Month Plan within 30 days. Criteria: MEDIUM severity (CVSS 4.0-6.9), lower exploitation probability. Include in regular patch cycle.

Monitor Track and reassess. Criteria: LOW severity (CVSS 0.1-3.9), minimal exploitation risk. No immediate action needed.

SSVC AssessmentENISA

SSVC Decision· derived

Scheduled

Exploitation· derived

Poc

System Exposure· derived

Open

Automatable· derived

Human Impact

High

Priority Score

Low Medium High Critical

KEV: 0

EPSS: 0

CVSS: +44

PoC: +20

Weaponized: 0

Threat intel: 0

Gov advisory: 0

Attack Technique

Buffer Overflow HIGH

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.

Stack-based Buffer Overflow HIGH

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.