Tenda W20E
CVE-2026-36822
HIGH
Attack ChainAIDerived
Hypothetical attack flow derived from CVE metadata – not a confirmed exploit chain
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AccessIdentify reachable W20E httpd on LAN/WAN
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DeliveryCraft HTTP request with oversized macAddr
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ExploitPOST to formDelStaState endpoint
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ExecutionOverflow stack buffer in handler
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PersistCrash httpd / management plane
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ImpactRouter DoS until reboot
Vulnerability Assessment
| Weakness |
CWE
ASVS 5.0
V15 - Secure Coding and Architecture Stack buffer bounds checking
MITRE ATT&CK
1 technique across 1 tactic: Execution The technique list with ATT&CK links and the kill-chain view is part of the Basic plan and up. |
| Exploitation Conditions | The attacker requires network reachability to the Tenda W20E's HTTP management interface (typically TCP/80 on the LAN-side gateway IP, or the WAN IP if remote web management is enabled in the router settings) and must be able to issue an HTTP request reaching the formDelStaState handler with an attacker-controlled macAddr parameter; per CVSS PR:N/UI:N no authentication or user interaction is required. Exploitation is limited to Tenda W20E units running firmware v15.11.0.6 (other firmware revisions are not confirmed vulnerable from the available data), and impact is bounded to denial of service - confidentiality and integrity are marked None in the CVSS vector, so credentials and configuration are not directly exposed by this issue. |
| Impact | The CVSS 3.1 vector AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H scores 7.5 (High) driven entirely by availability impact, reflecting an unauthenticated, low-complexity network-reachable DoS. Real-world risk is moderated by deployment context: Tenda W20E web administration is typically reachable only from the LAN, so internet-wide mass exploitation is unlikely unless WAN-side management is enabled. EPSS, KEV status, and SSVC decision data were not provided in the input, so probability of in-the-wild exploitation cannot be quantified; the only public artifact is a research repository (SemVulLLM) which suggests this was found via LLM-assisted vuln discovery rather than active attacker tooling. The CWE-121 classification combined with availability-only impact in CVSS suggests the researcher demonstrated a crash but did not establish reliable code execution - though stack overflows of this class can sometimes be escalated to RCE on embedded MIPS targets, which would warrant re-scoring; this should be verified against the PoC. |
| Exploit ScenarioDerived | An attacker with network reachability to the router's web interface - for example a guest on the same Wi-Fi network, or any internet host if remote management is enabled - sends a single crafted HTTP POST to the formDelStaState endpoint with an overly long macAddr value. The oversized parameter overflows the stack buffer inside httpd, crashing the management daemon and disrupting administrative access and dependent services until the device is rebooted or the watchdog restarts httpd. Research PoC material exists in the SemVulLLM GitHub repository, but no weaponized public exploit was identified at time of analysis. |
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Alert meAnalysisAIv1 – Jun 09, 2026
Denial of service in Tenda W20E router firmware v15.11.0.6 allows unauthenticated remote attackers to crash the device by sending a crafted HTTP request containing an oversized macAddr parameter to the formDelStaState handler. The flaw is a stack-based buffer overflow with high availability impact and no confidentiality/integrity loss per CVSS, and no public exploit identified at time of analysis beyond a research repository on GitHub.
RemediationAI
No vendor-released patch identified at time of analysis - Shenzhen Tenda has not published an advisory or fixed firmware build referenced in the provided data, and administrators should monitor https://www.tendacn.com/ for a successor to v15.11.0.6. As compensating controls, disable remote (WAN-side) web administration on the W20E so the httpd is only reachable from trusted LAN segments, and restrict LAN access to the management interface (typically 192.168.0.1) via firewall rules or VLAN segmentation to a dedicated admin workstation, accepting the trade-off that legitimate admins must connect from that segment. Where feasible, place the device behind an upstream reverse proxy or WAF that enforces a strict allowlist on macAddr (canonical 17-character MAC format) for any forwarded requests to formDelStaState, noting this may break legitimate management traffic if the field is used elsewhere. Researcher proof-of-concept material is at https://github.com/xhh0124/SemVulLLM/tree/main/W20E/formDelStaState and can be used to validate any mitigation.
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Technical ContextAI · show details
The Tenda W20E is a small/medium-business gigabit VPN router whose embedded web management interface exposes CGI-like handlers in its HTTP daemon (httpd). The vulnerable formDelStaState function is responsible for removing wireless station state entries and parses a macAddr parameter from incoming HTTP requests. CWE-121 (Stack-based Buffer Overflow) indicates that the parameter is copied into a fixed-size stack buffer without proper length validation, allowing adjacent stack data - including saved return addresses - to be overwritten. On MIPS-based Tenda devices, such overflows typically corrupt the saved $ra register and crash the httpd worker, producing a denial of service. The single CPE entry (cpe:2.3:a:n/a:n/a) is a placeholder and does not enumerate exact affected hardware/firmware combinations.
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Severity by source
AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Primary rating from Vendor (mitre) · only source for this CVE.
CVSS VectorVendor: mitre
Lifecycle Timeline
2DescriptionCVE.org
Shenzhen Tenda Technology Co., Ltd Tenda W20E v15.11.0.6 was discovered to contain a buffer overflow in the macAddr parameter of the formDelStaState function. This vulnerability allows attackers to cause a Denial of Service (DoS) via a crafted HTTP request.
Executive ViewAI
Tenda W20E routers running firmware v15.11.0.6 are vulnerable to unauthenticated remote denial-of-service attacks that crash affected devices, directly threatening network availability for organizations deploying this hardware. The vulnerability is remotely exploitable without authentication or user interaction, creating immediate operational risk. No vendor patch currently exists, requiring urgent compensating controls to maintain network continuity.
Implement firewall rules and ACLs restricting HTTP/HTTPS access to router management interfaces to authorized IPs only; disable remote management via HTTP/HTTPS if not operationally required; deploy intrusion detection signatures alerting on oversized macAddr parameters in HTTP requests; establish network segmentation limiting affected router communication scope; monitor for unexpected router restarts or connectivity losses; maintain asset inventory tracking firmware version compliance; document business continuity procedures for router failure scenarios.
Threat Intelligence Overview
NVD
CVE.org
EPSS
Vulnrichment
GitHub
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.
Denial of Service attacks render applications or systems unavailable by overwhelming resources or triggering failure conditions.
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