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TOTOLINK N600R EUVDEUVD-2026-66196

| CVE-2026-79911 CRITICAL
Stack-based Buffer Overflow (CWE-121)
2026-08-25 VulDB GHSA-wgfc-85p2-7526
9.3
CVSS 4.0 · Vendor: VulDB
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Severity by source

Vendor (VulDB) PRIMARY
9.3 CRITICAL
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H/E:P/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
vuln.today AI
9.8 CRITICAL

Network-reachable low-complexity stack overflow yielding code execution gives C/I/A:H; PR:N follows the reported vector but is uncertain since cstecgi.cgi often requires a session.

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

Primary rating from Vendor (VulDB).

CVSS VectorVendor: VulDB

CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H/E:P/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
X

Lifecycle Timeline

5
Analysis Updated
Aug 25, 2026 - 23:28 vuln.today
v2 (cvss_changed)
Re-analysis Queued
Aug 25, 2026 - 23:22 vuln.today
cvss_changed
CVSS changed
Aug 25, 2026 - 23:22 NVD
10.0 (CRITICAL) 9.3 (CRITICAL)
Analysis Generated
Aug 25, 2026 - 23:16 vuln.today
CVE Published
Aug 25, 2026 - 22:15 cve.org
CRITICAL 10.0

DescriptionCVE.org

A security vulnerability has been detected in TOTOLINK N600R 4.3.0cu.7647_B20210106. The affected element is the function setSystemConfig of the file /cgi-bin/cstecgi.cgi of the component CGI Handler. Such manipulation of the argument Hostname leads to stack-based buffer overflow. It is possible to launch the attack remotely. The exploit has been disclosed publicly and may be used.

AnalysisAI

Stack-based buffer overflow in the TOTOLINK N600R router (firmware 4.3.0cu.7647_B20210106) lets remote attackers corrupt memory by supplying an oversized Hostname argument to the setSystemConfig function in /cgi-bin/cstecgi.cgi, potentially enabling arbitrary code execution on the device. Publicly available exploit code exists (disclosed via VulDB and a GitHub write-up), though the flaw is not listed in CISA KEV. …

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Attack ChainAIDerived

Hypothetical attack flow derived from CVE metadata

Access
Reach router web management interface
Delivery
Send crafted POST to /cgi-bin/cstecgi.cgi
Exploit
Overflow Hostname buffer in setSystemConfig
Execution
Overwrite saved return address
Persist
Execute attacker code on device
Impact
Gain full router control

Vulnerability AssessmentAI

Exploitation Exploitation requires network reachability to the router's HTTP management service and the ability to call the setSystemConfig action of /cgi-bin/cstecgi.cgi with an attacker-controlled, oversized Hostname argument on firmware 4.3.0cu.7647_B20210106. … Additional conditions and limiting factors are described in the full assessment.
Risk Assessment The signals mostly agree this is a genuine, easily reachable flaw: the CVSS 4.0 vector (AV:N/AC:L/AT:N/PR:N/UI:N) indicates network-reachable, low-complexity exploitation with no authentication or user interaction, and the E:P (Proof-of-Concept) flag plus a published GitHub PoC confirm working exploit code. … Full risk analysis with EPSS, KEV, and SSVC signal comparison available after sign-in.
Exploit Scenario An attacker with network access to the router's management interface sends a crafted HTTP request to /cgi-bin/cstecgi.cgi invoking setSystemConfig with an overlong Hostname value, overflowing a stack buffer and hijacking control flow to run attacker-supplied code on the device. Because a public PoC and technical write-up already exist and CVSS complexity is low, a remote attacker could reliably crash the router or gain code execution; success yields full control of the gateway and the traffic passing through it.
Remediation No vendor-released patch identified at time of analysis; TOTOLINK has published no fixed firmware version in the provided data, so upgrade guidance cannot cite an exact build - monitor https://www.totolink.net/ for an updated N600R firmware release. … Detailed patch versions, workarounds, and compensating controls in full report.

Recommended ActionAI

Within 24 hours: Conduct inventory of all TOTOLINK N600R routers in production and confirm firmware version status; segregate affected devices from critical network segments if feasible. …

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EUVD-2026-66196 vulnerability details – vuln.today

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