What is the CVSS score of CVE-2026-4254?

CVE-2026-4254 has a CVSS 3.1 base score of 9.8 (Critical). CVSS vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H. EPSS exploitation probability: 0.0%.

How to fix or mitigate CVE-2026-4254?

Within 24 hours: Inventory all Tenda AC8 devices in your network and isolate affected units from critical systems. Within 7 days: Implement network segmentation to restrict router access and deploy WAF rules blocking HTTP requests to /goform/SysToolChangePwd endpoint. Within 30 days: Evaluate replacing vulnerable Tenda AC8 routers with patched alternatives or devices from alternative vendors, or deploy compensating controls if replacement is infeasible.

Tenda CVE-2026-4254

EUVD-2026-12488 CRITICAL

Buffer Overflow (CWE-119)

2026-03-16 cna@vuldb.com

Buffer Overflow Tenda

9.8

CVSS 3.1 · NVD

View

Attack ChainAIDerived

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

Access

Send crafted HTTP request to /goform/SysToolChangePwd
Exploit

Overflow local_2c parameter in doSystemCmd
Execution

Overwrite stack memory
Impact

Execute arbitrary code as root

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Weakness	CWE CWE-119 OWASP Top 10:2025 A06:2021 - Vulnerable and Outdated Components ASVS 5.0 V15 - Secure Coding and Architecture Bounds checking, buffer size validation MITRE ATT&CK 2 techniques across 2 tactics: Execution,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 AC8 router firmware version 16.03.50.11 or earlier with HTTP endpoint /goform/SysToolChangePwd accessible. No authentication required for vulnerable endpoint.
Impact	This vulnerability presents an extremely high real-world risk based on multiple factors: the CVSS 3.1 score of 9.8 indicates critical severity with network-based attack vector (AV:N), low complexity (AC:L), no privileges required (PR:N), and no user interaction needed (UI:N). The availability of a public proof-of-concept exploit significantly increases the likelihood of exploitation. While no EPSS score or KEV listing is mentioned in the provided data, the combination of unauthenticated remote exploitation, public exploit code, and the widespread deployment of consumer routers makes this a priority for immediate remediation. The technical impact is severe as successful exploitation grants full device control, potentially allowing attackers to intercept network traffic, modify DNS settings, or use the device as a pivot point for further attacks.
Exploit ScenarioDerived	An attacker can scan for exposed Tenda AC8 routers on the internet and send a specially crafted HTTP request to the /goform/SysToolChangePwd endpoint containing an oversized payload in the local_2c parameter. This triggers a buffer overflow that overwrites the stack, allowing the attacker to execute arbitrary code with the privileges of the web server process, typically resulting in full router compromise. The publicly available proof-of-concept at https://github.com/digitalandrew/tenda_ac8_v5/blob/main/CVE_Report_Tenda_AC8_SysToolChangePwd_BOF.md demonstrates the exploitation technique.

Act Now Prioritize within 24-48h. Why: CRITICAL severity.

No patch listed yet 0.0% exploitation probability (EPSS)

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AnalysisAIv1 – Mar 16, 2026

Remote code execution in Tenda AC8 firmware versions up to 16.03.50.11 results from a stack-based buffer overflow in the HTTP endpoint handling password change requests. An unauthenticated attacker can exploit this vulnerability over the network to execute arbitrary commands with full system privileges. Public exploit code exists for this vulnerability and no patch is currently available.

Earlier versions of this analysis (1)

v1 Mar 16, 2026 - 18:30 CVSS 9.8

A stack-based buffer overflow vulnerability exists in Tenda AC8 routers running firmware version 16.03.50.11 and earlier, affecting the password change functionality accessible via the HTTP endpoint /goform/SysToolChangePwd. The vulnerability allows remote attackers without authentication to achieve complete system compromise with high impact to confidentiality, integrity, and availability. A public proof-of-concept exploit is available on GitHub, making this vulnerability particularly dangerous for exposed devices.

RemediationAI

No patch or fixed firmware version has been identified in the available intelligence sources. Given the critical nature and public exploit availability, affected users should immediately disable remote management features and restrict administrative interface access to trusted local network segments only. Consider replacing the affected Tenda AC8 router with a device from a vendor with active security support if no patch becomes available. Monitor the vendor website at https://www.tenda.com.cn/ and the vulnerability references at https://vuldb.com/?id.351212 for updates on patch availability.

Affected VersionsENISA

AC8 16.03.50.9

AC8 16.03.50.4

AC8 16.03.50.1

AC8 16.03.50.10

AC8 16.03.50.6

AC8 16.03.50.11

AC8 16.03.50.2

AC8 16.03.50.8

AC8 16.03.50.3

AC8 16.03.50.5

AC8 16.03.50.7

AC8 16.03.50.0

Affected Packages

euvd ac8 no fix

Source: OSV (Open Source Vulnerabilities)

Affects your stack

Affects 1 package in euvd

Checking this CVE against your own stacks and servers is part of the Basic plan and up.

Technical ContextAI · show details

The vulnerability resides in the doSystemCmd function that processes HTTP requests to the /goform/SysToolChangePwd endpoint on Tenda AC8 wireless routers. The flaw is classified as CWE-119 (Improper Restriction of Operations within the Bounds of a Memory Buffer), a classic buffer overflow condition where user-supplied input to the local_2c argument is not properly validated before being copied to a fixed-size stack buffer. This allows attackers to overwrite adjacent memory locations on the stack, potentially including the return address, enabling arbitrary code execution. The affected Tenda AC8 is a consumer-grade wireless router commonly used in home and small office environments.

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Exploit and PoC references, threat intelligence from 22 sources

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Severity by source

NVD PRIMARY 9.8 CRITICAL

AV:N/AC:L/PR:N/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

None

User Interaction

None

Scope

Unchanged

Confidentiality

High

Integrity

High

Availability

High

DescriptionCVE.org

A weakness has been identified in Tenda AC8 up to 16.03.50.11. This vulnerability affects the function doSystemCmd of the file /goform/SysToolChangePwd of the component HTTP Endpoint. This manipulation of the argument local_2c causes stack-based buffer overflow. The attack can be initiated remotely. The exploit has been made available to the public and could be used for attacks.

Executive ViewAI

Why It Matters

A critical remote code execution vulnerability affects Tenda AC8 routers up to firmware version 16.03.50.11, allowing unauthenticated attackers to execute arbitrary commands. Organizations using this router model face immediate risk of network compromise, data exfiltration, and potential lateral movement into connected systems, with no vendor patch currently available.

Business Impact: Severe

Compensating Controls

Implement Web Application Firewall (WAF) rules to block all requests to /goform/SysToolChangePwd endpoint; restrict HTTP/HTTPS access to router management interface via network segmentation and IP whitelisting; disable remote management features if not required; deploy network intrusion detection/prevention systems (IDS/IPS) signatures targeting this CVE; monitor router access logs for suspicious activity; implement VPN-only access to router administration; consider disabling the affected SysToolChangePwd functionality if alternative management methods exist.

Threat Intelligence Overview

EPSS Score

0.0%

Top 86% exploitable

Data Quality

6 sources

Confidence: High

EUVD

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 CRITICAL

CISA KEV No

Public POC No

EPSS 0.0%

Patch available No

Active threat No

Deciding rule

CRITICAL severity

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

Out-of-Cycle

Exploitation· derived

None

System Exposure· derived

Open

Automatable· derived

Yes

Human Impact

Very High

Priority Score

Low Medium High Critical

KEV: 0

EPSS: 0

CVSS: +49

PoC: 0

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.