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TOTOLINK T6 CVE-2026-51705

| EUVDEUVD-2026-68644 CRITICAL
Improper Access Control (CWE-284)
2026-08-31 mitre GHSA-v239-2h64-5xhw
9.8
CVSS 3.1 · Vendor: mitre
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Attack ChainAIDerived

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

  1. Access
    Reach router web interface on LAN
  2. Delivery
    Craft POST to /cgi-bin/cstecgi.cgi (setWiFiMeshName)
  3. Exploit
    Handler skips authorization check
  4. Execution
    Mesh entry renamed
  5. Impact
    Config integrity altered

Vulnerability Assessment

Weakness
CWE
OWASP Top 10:2025
A01:2025 - Broken Access Control
ASVS 5.0
V8 - Authorization Access control enforcement
MITRE ATT&CK

1 technique across 1 tactic: Defense Evasion

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 TOTOLINK T6 web management endpoint /cgi-bin/cstecgi.cgi on firmware 4.1.5cu.748_B20211015 and the ability to send a crafted POST invoking the setWiFiMeshName function; no authentication, credentials, or user interaction are needed (PR:N/UI:N). The practical limiting factor is exposure: by default the interface is LAN-facing, so an attacker must be on the local network or the router must have remote/WAN administration enabled for internet-based exploitation. Impact is limited to renaming mesh entries - a configuration/integrity change, not code execution or data theft.

Impact

The published CVSS 9.8 (AV:N/AC:L/PR:N/UI:N/C:H/I:H/A:H) overstates real-world impact. The unauthenticated, low-complexity, network-reachable nature (AV:N/AC:L/PR:N/UI:N) is credible for the LAN-facing management interface, but the impact metrics are inflated: setWiFiMeshName is a write-only setter that renames a mesh entry, which is an integrity effect on configuration only - it does not read secrets (no genuine C:H) and does not by itself deny service (no clear A:H). A more defensible impact is integrity-limited. Corroborating signals point to low priority: EPSS is 0.18% (7th percentile), the flaw is NOT in CISA KEV, and no POC is referenced. The 'Authentication Bypass' tag is a loose fit - this is missing authorization on a specific handler, not a bypass of the auth mechanism. Net: a real but low-severity access-control defect, most relevant where the router's web UI is exposed beyond the trusted LAN.

Exploit ScenarioDerived

An attacker on the same LAN (or with reach to an internet-exposed management interface) sends a single crafted POST to http://<router>/cgi-bin/cstecgi.cgi invoking setWiFiMeshName with an arbitrary name, and the router applies the rename with no authentication. This could be used to relabel mesh nodes for confusion, social-engineering (spoofing a trusted network name in the admin view), or as one step in a broader unauthenticated-config-tampering campaign against the device. No POC is referenced, and complexity is low.

Act Now Prioritize within 24-48h. Why: CRITICAL severity.
No patch listed yet 0.2% exploitation probability (EPSS)

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AnalysisAIv1 – Sep 02, 2026

Unauthenticated configuration tampering in the TOTOLINK T6 router (firmware 4.1.5cu.748_B20211015) lets remote attackers invoke the setWiFiMeshName handler via a crafted POST to /cgi-bin/cstecgi.cgi with no credentials, renaming mesh network entries. The setter enforces no access control (CWE-284), so any host that can reach the web management interface can alter mesh labels. No public exploit is identified at time of analysis and EPSS is low (0.18%), consistent with a low-value config write rather than a device-takeover primitive.

RemediationAI

No vendor-released patched firmware version is identified at time of analysis; the referenced TOTOLINK pages are product/download portals rather than a versioned fix advisory, so monitor totolink.net for updated T6 firmware and apply it once published. As compensating controls: restrict access to the router's web management interface (/cgi-bin/cstecgi.cgi) to trusted management hosts only and ensure remote/WAN administration is disabled so the handler is not reachable from the internet (trade-off: none significant for home use, since WAN admin should be off by default); segment the router's LAN management VLAN away from untrusted or guest devices to limit who can reach the CGI endpoint (trade-off: added network configuration); and monitor for unexpected mesh-name changes as an indicator of tampering. Because the change is cosmetic/configuration-level, these access restrictions are the primary mitigation rather than emergency patching.

Affected VersionsENISA

n/a n/a

Affects your stack

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

Technical ContextAI · show details

The TOTOLINK T6 is a consumer mesh Wi-Fi router. Like most of the TOTOLINK T-series, it exposes a single CGI dispatcher at /cgi-bin/cstecgi.cgi that routes JSON/form requests to named handler functions by a 'topicurl'/function selector. The affected function, setWiFiMeshName, writes the display name of a mesh node/entry. The root cause is CWE-284 (Improper Access Control): the dispatcher invokes this setter without validating an authenticated session or CSRF token, so any request reaching the handler is honored. This is the same architectural weakness shared across the broad batch of TOTOLINK T6 cstecgi.cgi CVEs (getters that leak config and setters that mutate it without auth). The CPE 'cpe:2.3:a:n/a:n/a' is a placeholder - the real affected product is the TOTOLINK T6 firmware, not an 'n/a' vendor/product.

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  • Exploit and PoC references, threat intelligence from 22 sources

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Severity by source

Vendor (mitre) PRIMARY 9.8 CRITICAL
AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
vuln.today AI 5.3 MEDIUM

Unauthenticated LAN-reachable setter (AV:N/AC:L/PR:N/UI:N), but renaming a mesh entry is a limited integrity change with no confidentiality or availability impact.

3.1 AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N
4.0 AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N

Primary rating from Vendor (mitre).

CVSS VectorVendor: mitre

Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

Lifecycle Timeline

3
CVSS changed
Sep 02, 2026 - 19:22 NVD
9.8 (CRITICAL)
CVE Published
Aug 31, 2026 - 00:00 cve.org
CRITICAL 9.8
CVE Published
Aug 31, 2026 - 00:00 cve.org
UNKNOWN (no severity yet)

DescriptionCVE.org

Incorrect access control in the setWiFiMeshName function of TOTOLINK T6 4.1.5cu.748_B20211015 allows unauthenticated attackers to rename mesh entries via sending a crafted POST request to /cgi-bin/cstecgi.cgi.

Executive ViewAI

Why It Matters

TOTOLINK T6 routers (firmware 4.1.5cu.748_B20211015) allow unauthenticated remote attackers to rename mesh network identifiers through an unprotected web interface. While this does not enable device takeover or data exfiltration, it represents a configuration integrity loss that could degrade network usability and user trust in WiFi naming for organizations relying on mesh deployments.

Business Impact: Medium
Compensating Controls

No vendor-released patch identified at time of analysis. Interim mitigations: restrict network access to the router's web management interface via firewall ACLs, disable remote administration features, isolate affected TOTOLINK T6 devices to a trusted network segment, or replace with access-controlled mesh solutions that enforce authentication on configuration endpoints.

Threat Intelligence Overview

EPSS Score
0.2%
Top 93% exploitable
Prevalence
Low
consumer TOTOLINK mesh router, niche home-network footprint
Data Quality
5 sources
Confidence: Medium

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 0.2%
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
Scheduled
Exploitation
None
System Exposure· derived
Open
Automatable
Yes
Human Impact
Medium
Technical Impact
Total

Priority Score

49
Low Medium High Critical
KEV: 0
EPSS: 0
CVSS: +49
PoC: 0
Weaponized: 0
Threat intel: 0
Gov advisory: 0

Attack Technique

Authentication bypass attacks exploit flaws in the verification mechanisms that control access to systems and applications.

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