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T6 Firmware CVE-2025-6916

| EUVDEUVD-2025-19554 HIGH
Improper Authentication (CWE-287)
2025-06-30 cna@vuldb.com
7.4
CVSS 4.0 · NVD
View

Vulnerability Assessment

Weakness
CWE
OWASP Top 10:2025
A07:2025 - Authentication Failures
ASVS 5.0
V6 - Authentication Authentication mechanism validation
MITRE ATT&CK

2 techniques across 2 tactics: Defense Evasion, Initial Access

The technique list with ATT&CK links and the kill-chain view is part of the Basic plan and up.

This Week Schedule remediation this week. Why: HIGH severity (CVSS 7.0-8.9).
No patch listed yet 0.1% exploitation probability (EPSS)

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AnalysisAIv2 – Jul 26, 2026

Authentication bypass in TOTOLINK T6 router firmware 4.1.5cu.748_B20211015 allows adjacent network attackers to manipulate the authCode or goURL parameters to bypass authentication on the /formLoginAuth.htm endpoint. The vulnerability enables unauthorized access to administrative functions without credentials. Publicly available exploit code exists, but no active exploitation has been confirmed.

Earlier versions of this analysis (1)
v1 Mar 16, 2026 - 01:25 CVSS 8.8

Affected VersionsENISA

T6 4.1.5cu.748_B20211015

Affected Packages

euvd t6 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.

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  • Exploit and PoC references, threat intelligence from 22 sources

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Severity by source

NVD PRIMARY 7.4 HIGH
CVSS:4.0/AV:A/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:P

Primary rating from NVD · only source for this CVE.

CVSS VectorNVD

Attack Vector
Adjacent
Attack Complexity
Low
Attack Requirements
None
Privileges Required
None
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

4
CVSS changed
Apr 29, 2026 - 01:11 NVD
8.8 (HIGH) 7.4 (HIGH)
PoC Detected
Jul 07, 2025 - 14:41 vuln.today
Public exploit code
CVE Published
Jun 30, 2025 - 17:15 cve.org
HIGH 7.4
CVE Published
Jun 30, 2025 - 17:15 nvd
HIGH 8.8

DescriptionCVE.org

A vulnerability, which was classified as critical, was found in TOTOLINK T6 4.1.5cu.748_B20211015. This affects the function Form_Login of the file /formLoginAuth.htm. The manipulation of the argument authCode/goURL leads to missing authentication. The attack needs to be initiated within the local network. The exploit has been disclosed to the public and may be used.

Executive ViewAI

Why It Matters

CVE-2025-6916 presents significant security risk, a improper authentication vulnerability rated CVSS 8.8. Attackers could bypass security controls to gain unauthorized access to protected resources and sensitive data. Proof-of-concept code is publicly available, increasing the risk of exploitation. Organizations should apply vendor updates when available and consider compensating controls in the interim.

Recommended Action

Within 7 days: Identify all affected systems and apply vendor patches promptly. Audit authentication configurations and rotate any potentially compromised credentials.

Business Impact: Severe
Compensating Controls

Apply vendor patch. If immediate patching is not feasible: (1) Implement network-level access controls; (2) Enable MFA where possible; (3) Monitor authentication logs for anomalous access.

Threat Intelligence Overview

EPSS Score
0.1%
Top 69% 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 0.1%
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
Controlled
Automatable· derived
No
Human Impact
Very 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

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

CVE-2023-7221 CRITICAL POC
9.8 Jan 09

A vulnerability was found in Totolink T6 4.1.9cu.5241_B20210923. Rated critical severity (CVSS 9.8), this vulnerability

CVE-2022-38828 CRITICAL POC
9.8 Sep 16

TOTOLINK T6 V4.1.5cu.709_B20210518 is vulnerable to command injection via cstecgi.cgi. Rated critical severity (CVSS 9.8

CVE-2022-38827 CRITICAL POC
9.8 Sep 16

TOTOLINK T6 V4.1.5cu.709_B20210518 is vulnerable to Buffer Overflow via cstecgi.cgi. Rated critical severity (CVSS 9.8),

CVE-2022-38826 CRITICAL POC
9.8 Sep 16

In TOTOLINK T6 V4.1.5cu.709_B20210518, there is an execute arbitrary command in cstecgi.cgi. Rated critical severity (CV

CVE-2022-38823 CRITICAL POC
9.8 Sep 16

In TOTOLINK T6 V4.1.5cu.709_B20210518, there is a hard coded password for root in /etc/shadow.sample. Rated critical sev

CVE-2022-25084 CRITICAL POC
9.8 Feb 24

TOTOLink T6 V5.9c.4085_B20190428 was discovered to contain a command injection vulnerability in the "Main" function. Rat

CVE-2025-7460 HIGH POC
8.8 Jul 11

CVE-2025-7460 is a critical buffer overflow vulnerability in the setWiFiAclRules function of TOTOLINK T6 routers (versio

CVE-2022-32053 HIGH POC
7.5 Jul 01

TOTOLINK T6 V4.1.9cu.5179_B20201015 was discovered to contain a stack overflow via the cloneMac parameter in the functio

CVE-2022-32052 HIGH POC
7.5 Jul 01

TOTOLINK T6 V4.1.9cu.5179_B20201015 was discovered to contain a stack overflow via the desc parameter in the function FU

CVE-2022-32051 HIGH POC
7.5 Jul 01

TOTOLINK T6 V4.1.9cu.5179_B20201015 was discovered to contain a stack overflow via the desc, week, sTime, eTime paramete

CVE-2022-32050 HIGH POC
7.5 Jul 01

TOTOLINK T6 V4.1.9cu.5179_B20201015 was discovered to contain a stack overflow via the cloneMac parameter in the functio

CVE-2022-32049 HIGH POC
7.5 Jul 01

TOTOLINK T6 V4.1.9cu.5179_B20201015 was discovered to contain a stack overflow via the url parameter in the function FUN

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