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Tenda F456 CVE-2026-9389

| EUVDEUVD-2026-31545 HIGH
Classic Buffer Overflow (CWE-120)
2026-05-24 VulDB GHSA-65p4-www8-vqx4
7.4
CVSS 4.0 · Vendor: VulDB
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Attack ChainAIDerived

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

  1. Access
    Identify exposed F456 admin interface
  2. Delivery
    Obtain low-privilege web UI credentials
  3. Exploit
    Send crafted POST to /goform/L7Im with oversized page parameter
  4. Execution
    Trigger buffer overflow in frmL7ImForm
  5. Persist
    Corrupt httpd memory for DoS or code execution
  6. Impact
    Pivot into LAN or persist on router

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

Attacker must have network reachability to the F456's HTTP management interface and valid low-privilege credentials to the router web UI (CVSS PR:L). The target must be running firmware 1.0.0.5 and have the /goform/L7Im endpoint exposed to the attacker's network position - typically the LAN side, since SOHO routers usually do not expose admin HTTP to the WAN by default. No user interaction is required (UI:N) and attack complexity is low (AC:L/AT:N). Exploitation is LIMITED by: the authentication requirement, the niche deployment footprint of this specific Tenda model, and the lack of any documented unauthenticated chain that would expose the bug to anonymous internet scanners.

Impact

The CVSS 4.0 vector AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H scores 7.4 - network-reachable, low complexity, but requiring low-level privileges (PR:L), meaning an attacker needs at least authenticated access to the router's web UI before triggering the overflow. EPSS is very low (0.05%, percentile 14%) and the CVE is not in CISA KEV, indicating no observed in-the-wild campaigns despite the public PoC on GitHub. SSVC signals were not provided in the input, but the combination of authenticated precondition, niche SOHO product, and absence of KEV listing suggests this is a moderate-priority defensive concern rather than an emergency: the high CIA impact (VC:H/VI:H/VA:H) is real, but exploitation is gated by the need for valid credentials or a chained auth bypass, neither of which is documented here. Note the scope-unchanged flags (SC:N/SI:N/SA:N) - impact is confined to the router itself.

Exploit ScenarioDerived

An attacker with low-privilege credentials to the F456 web UI - obtained via phishing, default/reused passwords, or a separate auth bypass - sends a crafted POST to /goform/L7Im with an oversized page argument, triggering the buffer overflow in frmL7ImForm. Using the publicly disclosed PoC at github.com/Litengzheng/vuldb_new, the attacker crashes the router's HTTP daemon for denial of service, or with additional exploitation effort attempts to hijack control flow inside the httpd process to gain code execution on the device. A compromised router could then be used to pivot into the LAN, intercept traffic, or be conscripted into a botnet.

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 – Jun 08, 2026

Buffer overflow in the Tenda F456 router (firmware 1.0.0.5) allows remote attackers with low privileges to corrupt memory via the page parameter handled by the frmL7ImForm function exposed at /goform/L7Im. Publicly available exploit code exists, though EPSS rates near-term exploitation probability at only 0.05% (14th percentile) and the issue is not listed in CISA KEV.

RemediationAI

No vendor-released patch identified at time of analysis - neither the VulDB references nor the EUVD entry cite a fixed firmware build for the Tenda F456. Until Tenda publishes updated firmware, restrict reachability of the management interface by disabling remote/WAN-side administration (blocking inbound access to the device's HTTP/HTTPS admin port from untrusted networks), placing the router's LAN management plane on a segmented VLAN, and enforcing strong, unique administrator credentials since exploitation requires PR:L authenticated access. Where feasible, place an ACL or upstream firewall rule blocking external requests to the /goform/L7Im endpoint specifically; the side effect is loss of any legitimate remote management that traverses that path. Monitor Tenda's advisory page (https://www.tenda.com.cn/) and the NVD record (https://nvd.nist.gov/vuln/detail/CVE-2026-9389) for firmware updates, and consider replacing the device if the vendor does not issue a fix.

Affected VersionsENISA

F456 1.0.0.5

Affected Packages

euvd f456 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 Tenda F456 is a SOHO/SMB router whose web management interface processes form submissions through goform endpoints implemented in the device's HTTP server. The vulnerable handler frmL7ImForm parses the page argument supplied to /goform/L7Im without enforcing proper bounds, triggering CWE-120 (Classic Buffer Overflow - copying input to a fixed-size buffer without length checks). On embedded MIPS/ARM router firmware, this class of flaw commonly enables memory corruption that can degrade service or, with sufficient exploit engineering, divert control flow within the httpd process running as root. The affected product is identified by CPE cpe:2.3:a:tenda:f456:*:*:*:*:*:*:*:* and the only confirmed affected firmware per ENISA EUVD-2026-31545 is F456 1.0.0.5.

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  • Exploit and PoC references, threat intelligence from 22 sources

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Severity by source

Vendor (VulDB) PRIMARY 7.4 HIGH
CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:P

Primary rating from Vendor (VulDB) · only source for this CVE.

CVSS VectorVendor: VulDB

Attack Vector
Network
Attack Complexity
Low
Attack Requirements
None
Privileges Required
Low
User Interaction
None
Vulnerable system: Confidentiality
High
Vulnerable system: Integrity
High
Vulnerable system: Availability
High
Subsequent system: Confidentiality
None
Subsequent system: Integrity
None
Subsequent system: Availability
None

Lifecycle Timeline

1
CVSS changed
May 26, 2026 - 20:07 NVD
8.8 (HIGH) 7.4 (HIGH)

DescriptionCVE.org

A security vulnerability has been detected in Tenda F456 1.0.0.5. This affects the function frmL7ImForm of the file /goform/L7Im. The manipulation of the argument page leads to buffer overflow. The attack can be initiated remotely. The exploit has been disclosed publicly and may be used.

Executive ViewAI

Why It Matters

Tenda F456 routers (firmware 1.0.0.5) contain a buffer overflow vulnerability (CVSS 7.4) in the L7 packet filtering interface that allows low-privileged attackers to corrupt router memory via a single network request. Organizations using this model face potential network disruption or device compromise; the public availability of working exploit code accelerates the timeline to mass exploitation despite current low EPSS probability.

Business Impact: High
Compensating Controls

Network segmentation (restrict router management access to trusted administrative networks only); rate limiting on the /goform/L7Im endpoint to slow exploitation attempts; disable remote management features if not required; real-time monitoring for unexpected router reboots or memory errors. Publicly available exploit code elevates risk despite low near-term EPSS; compensating controls are temporary until vendor patch becomes available.

Threat Intelligence Overview

EPSS Score
0.0%
Top 86% exploitable
Exploit
POC
Public exploit code exists
Data Quality
6 sources
Confidence: High

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
No
Human Impact
High

Priority Score

57
Low Medium High Critical
KEV: 0
EPSS: 0
CVSS: +37
PoC: +20
Weaponized: 0
Threat intel: 0
Gov advisory: 0

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.

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