Tenda W20E
CVE-2026-36818
HIGH
Attack ChainAIDerived
Hypothetical attack flow derived from CVE metadata – not a confirmed exploit chain
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AccessIdentify exposed W20E management interface
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DeliveryCraft oversized wewifiWhiteUserInfo HTTP parameter
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ExploitPOST to formAddWewifiWhiteUser endpoint
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ExecutionOverflow buffer in form handler
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PersistCrash httpd / reboot device
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ImpactSustain DoS by repeating request
Vulnerability Assessment
| Weakness |
CWE
ASVS 5.0
V15 - Secure Coding and Architecture Buffer copy size validation
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 must be able to send an HTTP request to the W20E web management interface hosting the formAddWewifiWhiteUser endpoint, and the target device must be running firmware v15.11.0.6; no authentication, user interaction, or special privileges are required per the CVSS vector (AV:N/AC:L/PR:N/UI:N). Exploitation is limited in practice by whether the management interface is reachable from the attacker's network position - in default deployments it is typically bound to the LAN, so internet-wide exploitation requires that the operator has enabled WAN-side remote management or otherwise exposed the admin HTTP service. |
| Impact | Signals are mixed but lean toward low operational urgency. The CVSS 3.1 vector (AV:N/AC:L/PR:N/UI:N/C:N/I:N/A:H) rates 7.5 High because the attack is remote, low-complexity, unauthenticated, and produces full availability impact, but the impact is limited to a single router crash with no confidentiality or integrity loss. EPSS is only 0.02% (4th percentile) and the vulnerability is not in CISA KEV, so there is no public exploit identified at time of analysis beyond a research-style proof in the referenced GitHub repository. The realistic risk depends heavily on exposure: if the W20E web interface is reachable from the WAN/internet the device can be repeatedly crashed for sustained DoS, but in typical deployments management is bound to the LAN, reducing real-world reach. Note that the CPE is uninformative (n/a:n/a), so automated asset matching tools may fail to flag affected devices - defenders must rely on the textual product/version. |
| Exploit ScenarioDerived | An attacker who can reach the W20E web management interface (e.g., on a device with WAN-side management enabled, or an insider on the LAN) sends a single crafted HTTP request to the formAddWewifiWhiteUser handler with an overlong wewifiWhiteUserInfo parameter, overflowing the target buffer and crashing the httpd or the device itself. Repeating the request in a loop keeps the router offline, disrupting Wi-Fi and routing for all downstream users. A research proof-of-concept is published in the referenced GitHub repository, lowering the bar for reproduction, though no weaponized exploit kit is known. |
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Alert meAnalysisAIv1 – Jun 10, 2026
Remote denial of service in Tenda W20E router firmware v15.11.0.6 allows unauthenticated network attackers to crash the device by sending a crafted HTTP request that triggers a buffer overflow in the wewifiWhiteUserInfo parameter handled by the formAddWewifiWhiteUser function. EPSS scores exploitation probability at only 0.02% (4th percentile) and no public exploit code or active exploitation has been reported, though a research repository documenting the finding exists on GitHub. The vulnerability is not listed in CISA KEV.
RemediationAI
No vendor-released patch identified at time of analysis - Tenda has not published an advisory or fixed firmware in the supplied data, so the primary action is to monitor https://www.tendacn.com for an updated W20E firmware build that supersedes v15.11.0.6 and apply it once available. As compensating controls, ensure the device's web management interface is not exposed to the WAN (disable any remote-management option), restrict HTTP/HTTPS access to the management LAN segment via ACLs or firewall rules so that only trusted administrative hosts can reach the formAddWewifiWhiteUser endpoint, and consider placing the router behind an upstream device that can rate-limit or filter oversized POST parameters; the trade-off is loss of remote administration convenience and potential interference with legitimate large form submissions. Operators should also subscribe to vendor security notifications and consider replacing end-of-life W20E units if no fix materializes. Reference: https://github.com/xhh0124/SemVulLLM/tree/main/W20E/formAddWewifiWhiteUser for technical detail.
Affects your stack
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Technical ContextAI · show details
The Tenda W20E is a small-business/enterprise wireless gateway whose web management interface exposes form handlers such as formAddWewifiWhiteUser, used to manage a whitelist of permitted Wi-Fi users. The flaw maps to CWE-120 (Classic Buffer Overflow / Buffer Copy without Checking Size of Input): the wewifiWhiteUserInfo HTTP parameter is copied into a fixed-size stack or heap buffer without proper bounds validation, allowing an oversized value to corrupt adjacent memory and crash the httpd process. The provided CPE string (cpe:2.3:a:n/a:n/a:*) is a placeholder and does not include a vendor/product identifier, so affected scope must be derived from the description (W20E v15.11.0.6) rather than from authoritative CPE matching.
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Severity by source
AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Remote unauthenticated HTTP request with no user interaction crashes the router (A:H); no confidentiality or integrity impact and scope unchanged within the device.
Primary rating from Vendor (mitre).
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 wewifiWhiteUserInfo parameter of the formAddWewifiWhiteUser function. This vulnerability allows attackers to cause a Denial of Service (DoS) via a crafted HTTP request.
Executive ViewAI
Tenda W20E router devices in your network could be remotely disabled by attackers, potentially causing network outages if these routers are critical to operations. While the likelihood of attack is currently low, the absence of a vendor patch means organizations must implement workarounds or plan device replacements to fully mitigate this availability risk.
No vendor-released patch identified at time of analysis. Interim mitigations: restrict network access to management interfaces via segmentation or ACLs, deploy IDS/WAF detection rules for exploitation attempts against the wewifiWhiteUserInfo parameter, enable device logging and monitoring for unexpected crashes, and prioritize replacement of affected devices supporting critical network infrastructure.
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.
Denial of Service attacks render applications or systems unavailable by overwhelming resources or triggering failure conditions.
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