Tenda W3 Router
CVE-2026-36794
HIGH
Attack ChainAIDerived
Hypothetical attack flow derived from CVE metadata – not a confirmed exploit chain
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AccessReach router web UI on LAN or WAN
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DeliverySend crafted HTTP login request
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ExploitOversized username/password overflows stack buffer
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ExecutionR7WebsSecurityHandler corrupts httpd stack
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Persisthttpd process crashes or device reboots
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ImpactManagement interface and routing disrupted
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 | Exploitation requires network reachability to the HTTP management interface of a Tenda W3 router running firmware v1.0.0.3(2204), and the ability to send a crafted HTTP request whose username or password parameter is long enough to overflow the stack buffer in R7WebsSecurityHandler. No authentication, user interaction, or non-default settings are required on the LAN-facing web UI (PR:N/UI:N), so any host on the same LAN segment can trigger the crash. The principal limiting factor is exposure: by default the web UI is only reachable from the LAN, so internet exploitation depends on the user having explicitly enabled WAN-side remote management; the impact is also limited to availability (C:N/I:N/A:H), with no confirmed path to code execution or data disclosure from the available data. |
| Impact | Signals are mixed but lean toward limited real-world urgency. The CVSS vector (AV:N/AC:L/PR:N/UI:N) describes a trivially reachable, unauthenticated network attack with high availability impact, which on paper is a 7.5 priority. However, EPSS is only 0.01% (2nd percentile), the CVE is not on the CISA KEV list, and no public exploit was identified - consistent with a research-disclosure DoS against a consumer router rather than a mass-exploited flaw. The attack surface is also bounded: routers typically expose the web UI only on the LAN side by default, so 'network' in CVSS realistically means LAN-adjacent unless WAN-side remote management is enabled. The most important data gap is patch availability - the only reference is a researcher's PoC repository on GitHub, with no Tenda advisory linked - so defenders cannot currently verify whether a fixed firmware exists. |
| Exploit ScenarioDerived | An attacker on the same LAN (or on the internet if remote web management is enabled) sends a single crafted HTTP request to the router's authentication endpoint with an oversized username or password value, overflowing a stack buffer inside R7WebsSecurityHandler and crashing the httpd process. The router's web UI becomes unavailable and, depending on watchdog behavior, the device may reboot or drop traffic, disrupting the network until manual recovery. No authentication is required and the available references include a researcher repository with analysis artifacts, but no weaponized public exploit was identified at the time of analysis. |
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Alert meAnalysisAIv1 – Jun 10, 2026
Denial of service in Tenda W3 Wireless Router firmware v1.0.0.3(2204) allows unauthenticated remote attackers to crash the device by sending crafted HTTP requests with oversized username or password parameters that overflow stack buffers in the R7WebsSecurityHandler function. The flaw affects the router's web management interface and carries a CVSS 7.5 (availability-only impact); no public exploit identified at time of analysis and EPSS exploitation probability is very low at 0.01%.
RemediationAI
No vendor-released patch identified at time of analysis; defenders should monitor Tenda's support site (tendacn.com) for a firmware update addressing R7WebsSecurityHandler and apply it to W3 devices on v1.0.0.3(2204) as soon as it is published. Until a fix is available, the most effective compensating control is to disable WAN-side remote management on the web UI so the vulnerable handler is not reachable from the internet, and to restrict LAN-side access to the admin interface to a management VLAN or a small set of trusted hosts - the trade-off is that legitimate remote administration and casual LAN-based configuration become more cumbersome. Network operators can additionally rate-limit or drop oversized POSTs to the login endpoint at an upstream firewall, accepting the risk that some legitimate but long credentials may be blocked. For environments that cannot accept ongoing DoS risk, replacing the device is the only durable mitigation given the residual unauthenticated exposure and the absence of a vendor fix; reference the researcher PoC at https://github.com/xhh0124/SemVulLLM/tree/main/W3/R7WebsSecurityHandler for indicators useful in detection tuning.
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Technical ContextAI · show details
The vulnerability resides in R7WebsSecurityHandler, a request-handling routine in the embedded GoAhead-derived web server used by Tenda's consumer SOHO routers. The function processes login parameters (username and password) from incoming HTTP requests and copies them into fixed-size stack buffers without proper length validation, matching CWE-121 (Stack-based Buffer Overflow). Because the overflow corrupts stack memory in the httpd process, the most consistent observed outcome is a process crash and device-wide service disruption; on MIPS-based embedded targets like the W3, mitigations such as stack canaries and ASLR are commonly weak or absent, but the CVSS impact metrics (C:N/I:N/A:H) indicate availability impact only - code execution has not been claimed by the reporter. CPE data in the feed is a placeholder (cpe:2.3:a:n/a:n/a) and does not contain a usable product identifier, so affected scope must be taken from the description text.
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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 W3 Wireless Router v1.0.0.3(2204) was discovered to contain multiple stack overflows in the R7WebsSecurityHandler function via the username and password parameters. These vulnerabilities allow attackers to cause a Denial of Service (DoS) via a crafted HTTP request.
Executive ViewAI
Tenda W3 Wireless Router firmware v1.0.0.3(2204) contains a denial-of-service vulnerability allowing unauthenticated remote attackers to crash the device through malformed HTTP requests, disrupting network connectivity across affected locations. No public exploit has been identified at time of analysis, but the absence of vendor patches prolongs the exposure window and increases operational risk. With extremely low exploitation probability (0.01% EPSS) and device availability impact only, immediate action focuses on inventory, access controls, and patch availability verification.
Restrict remote web management interface (TCP 80/443) access to whitelisted administrator IP addresses using firewall rules; implement network segmentation for router management traffic; enable detailed access and syslog monitoring; consider disabling remote web management if not operationally necessary; establish baseline device monitoring to detect unexpected reboots or availability issues.
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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