CVE-2026-51690Network attack vector

Unauthenticated connectivity disruption via unchecked WAN changes

Published Aug 31, 2026 · Updated Sep 2, 2026

Incorrect access control in TOTOLINK T6 4.1.5cu.748_B20211015 allows remote attackers to disrupt connectivity via a crafted POST request. The cstecgi.cgi handler routes topicurl=setWanCfg to setWanCfg without requiring authentication and applies attacker-supplied WAN parameters. Network reachability to the management endpoint is sufficient to change upstream provisioning and interrupt the router's WAN connectivity.

CVSS severity9.1
Critical
EPSS probability0.36%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
Coverage for this vulnerability

See if you're affected

Explore vulnerability checks for your environment with Hinoki.

Book a demo

Summary

What happened

Incorrect access control in TOTOLINK T6 4.1.5cu.748_B20211015 allows remote attackers to disrupt connectivity via a crafted POST request. The cstecgi.cgi handler routes topicurl=setWanCfg to setWanCfg without requiring authentication and applies attacker-supplied WAN parameters. Network reachability to the management endpoint is sufficient to change upstream provisioning and interrupt the router's WAN connectivity.

The record

CVE
CVE-2026-51690
Published
Aug 31, 2026
Updated
Sep 2, 2026
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-284, T1565
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Aug 31, 2026CVE publishedPublication date reported by the CVE source.
  2. Sep 2, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

Affected buildAffected product and version details are unavailable.

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

9.1NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-284Improper Access Control
T1565Data Manipulation

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

See the directory against your own environment.

Your stack

Check the software in your environment

Book a demo to see how Hinoki identifies affected software and validates exploitability in your environment.

Book a demo