EUVD-2026-68533
GHSA-537g-8cpm-mc3r
Attack ChainAIDerived
Hypothetical attack flow derived from CVE metadata – not a confirmed exploit chain
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AccessReach router web interface (LAN or exposed WAN)
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ExploitSend crafted POST to /cgi-bin/cstecgi.cgi
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ExecutionInvoke getSlaveUpdate without authentication
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ImpactRead slave upgrade status and alter upgrade bookkeeping
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 management web server and the ability to send a POST request to the /cgi-bin/cstecgi.cgi endpoint targeting the getSlaveUpdate function; per the CVSS vector (PR:N/UI:N) no authentication and no user interaction are needed. The practical limiting factor is exposure of that management interface: on a default configuration the web UI is bound to the LAN, so a remote internet attacker must first find a device with remote/WAN management enabled, whereas a LAN-adjacent attacker (or one pivoting through another compromised host) can reach it directly. The condition is also constrained to the specific firmware build 4.1.5cu.748_B20211015 named in the report. |
| Impact | The signals here conflict and must be reconciled rather than taken at face value. The input CVSS 3.1 vector (AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H = 9.8) advertises a critical, fully unauthenticated remote compromise, but the description scopes the actual capability to querying slave upgrade status and affecting 'upgrade bookkeeping' - outcomes far closer to low confidentiality and low integrity impact than to high/high/high with no availability effect at all. There is no EPSS score provided, the vulnerability is not listed in CISA KEV, and no proof-of-concept or exploit code is referenced, so there is no public exploit identified at time of analysis. The realistic priority is therefore moderate: the pre-authentication network reachability is genuinely concerning for an edge device, so even a mid-sized operator should not ignore it, but the inflated C/I/A metrics should be treated skeptically and verified against the vendor advisory before it is queued as an emergency. This reads as a real-but-overscored access-control bug rather than a confirmed high-real-risk RCE. |
| Exploit ScenarioDerived | An attacker who can reach the router's web interface - from the LAN, or from the internet if remote management is exposed - sends a crafted unauthenticated POST to /cgi-bin/cstecgi.cgi invoking getSlaveUpdate, retrieving slave-node upgrade status and manipulating the upgrade bookkeeping state without logging in. No public proof-of-concept is available, and the low attack complexity means a working request, once derived, could be scripted trivially against reachable devices. |
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Alert meAnalysisAIv1 – Sep 01, 2026
Broken access control in the getSlaveUpdate function of the TOTOLINK T6 router (firmware 4.1.5cu.748_B20211015) lets unauthenticated attackers reach a privileged CGI handler over the network and read slave-device upgrade status while tampering with upgrade bookkeeping. The flaw is exposed via crafted POST requests to /cgi-bin/cstecgi.cgi and requires no credentials, though no public exploit code has been identified and it is not in CISA KEV. Note that the recorded CVSS of 9.8 appears materially higher than the limited impact the description actually details.
RemediationAI
No vendor-released patched firmware version is identified in the available data, so no fixed build can be cited with confidence - monitor the TOTOLINK download portal (https://www.totolink.net/home/menu/detail/menu_listtpl/download/id/190/ids/36.html) and the vendor-coordination trackers (github.com/DarkBoulder/CVE-Vendor-Coordination and github.com/ShengWu00/CVE-Vendor-Coordination) for a T6 release superseding 4.1.5cu.748_B20211015. As compensating controls, block all WAN-side access to the router's HTTP management interface and specifically deny external requests to /cgi-bin/cstecgi.cgi (trade-off: none for typical users, since remote web management should be off by default on a home router), restrict LAN management to trusted hosts or a management VLAN to limit which internal clients can reach the CGI endpoint, and disable remote/cloud management features if enabled. Given this is an edge device with a history of cstecgi.cgi weaknesses, treat replacement with a supported model as the durable option if no firmware fix appears.
Affected VersionsENISA
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Technical ContextAI · show details
The TOTOLINK T6 is a consumer/SOHO mesh Wi-Fi router whose web management plane is served by a single CGI dispatcher, /cgi-bin/cstecgi.cgi, which routes JSON/POST requests to named internal functions. Here the getSlaveUpdate function - part of the multi-node (master/slave) firmware upgrade coordination logic - fails to enforce an authentication or authorization check before executing. This is a textbook CWE-284 (Improper Access Control) issue: a sensitive operation is reachable by callers who should have been rejected at the boundary. The cstecgi.cgi dispatcher has historically been the focal point of numerous TOTOLINK access-control and injection findings because many of its sub-functions individually neglect session validation.
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Severity by source
AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Unauthenticated network access to the CGI is real (AV:N/AC:L/PR:N/UI:N), but the described impact is limited to reading upgrade status and altering bookkeeping, so C:L/I:L and A:N rather than the input's H/H/H.
Primary rating from Vendor (mitre).
CVSS VectorVendor: mitre
Lifecycle Timeline
3DescriptionCVE.org
Incorrect access control in the getSlaveUpdate function of TOTOLINK T6 4.1.5cu.748_B20211015 allows unauthenticated attackers to query slave upgrade status and affect upgrade bookkeeping via sending a crafted POST request to /cgi-bin/cstecgi.cgi.
Executive ViewAI
TOTOLINK T6 routers running firmware 4.1.5cu.748_B20211015 are vulnerable to unauthenticated remote attacks that can disrupt firmware update operations, potentially affecting device reliability and maintenance windows. The absence of a vendor patch requires immediate compensating controls to isolate affected routers from untrusted networks. Organizations should prioritize network containment while evaluating replacement device options.
Restrict network access to router management interfaces using firewall rules blocking unauthenticated POST requests to /cgi-bin/cstecgi.cgi; implement VPN-only or management-network-only access for router administration; enable comprehensive logging and alerting on router management access attempts; segregate router management traffic from production networks; maintain a detailed inventory of TOTOLINK T6 devices and firmware versions for rapid response; monitor for abnormal device behavior that may indicate exploitation attempts.
Threat Intelligence Overview
NVD
CVE.org
EPSS
Vulnrichment
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
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