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A3700r Firmware CVE-2026-1143

HIGH
Buffer Overflow (CWE-119)
2026-01-19 cna@vuldb.com
8.8
CVSS 3.1 · NVD
View

Attack ChainAIDerived

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

  1. Access
    Authenticate to TOTOLINK router
  2. Delivery
    Send crafted HTTP POST request to /cgi-bin/cstecgi.cgi
  3. Exploit
    Inject oversized ssid parameter into setWiFiEasyGuestCfg function
  4. Execution
    Overflow buffer memory
  5. Impact
    Execute arbitrary code

Vulnerability Assessment

Weakness
CWE
OWASP Top 10:2025
A06:2021 - Vulnerable and Outdated Components
ASVS 5.0
V15 - Secure Coding and Architecture Bounds checking, buffer size validation
MITRE ATT&CK

2 techniques across 2 tactics: Execution, Privilege Escalation

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

Exploitation Conditions

TOTOLIK A3700R firmware version 9.1.2u.5822_B20200513 with guest WiFi configuration feature enabled. Attacker requires valid login credentials to access /cgi-bin/cstecgi.cgi endpoint. Target must accept HTTP requests to cgi-bin directory.

Impact

CVSS 8.8 (HIGH). Attack vector: Network. Complexity: Low. Privileges required: Low. User interaction: None. Exploitable via remote/network. Public exploit/POC available.

Exploit ScenarioDerived

A remote attacker could exploit this vulnerability to buffer overflow.

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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AnalysisAIv1 – Mar 12, 2026

Buffer overflow in TOTOLIK A3700R firmware version 9.1.2u.5822_B20200513 allows authenticated remote attackers to achieve complete system compromise through manipulation of the ssid parameter in the WiFi guest configuration function. Public exploit code exists for this vulnerability and no patch is currently available. An attacker with network access and valid credentials can execute arbitrary code with full system privileges.

Earlier versions of this analysis (1)
v1 Mar 12, 2026 - 21:54 CVSS 8.8

A weakness has been identified in TOTOLINK A3700R 9.1.2u.5822_B20200513. This affects the function setWiFiEasyGuestCfg of the file /cgi-bin/cstecgi.cgi. [CVSS 8.8 HIGH]

RemediationAI

Monitor vendor advisories for a patch. Enable ASLR, DEP/NX, and stack canaries where possible. Restrict network access to the affected service where possible.

Affects your stack

Find out whether the stacks and servers you run are on an affected version.

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

Technical ContextAI · show details

Classified as CWE-119 (Buffer Overflow). Affects A3700R Firmware. A weakness has been identified in TOTOLINK A3700R 9.1.2u.5822_B20200513. This affects the function setWiFiEasyGuestCfg of the file /cgi-bin/cstecgi.cgi. Executing a manipulation of the argument ssid can lead to buffer overflow. The attack may be launched remotely. The exploit has been made available to the public and could be used for attacks.

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  • Exploit and PoC references, threat intelligence from 22 sources

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Severity by source

NVD PRIMARY 8.8 HIGH
AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Primary rating from NVD · only source for this CVE.

CVSS VectorNVD

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

Lifecycle Timeline

2
PoC Detected
Jan 29, 2026 - 18:31 vuln.today
Public exploit code
CVE Published
Jan 19, 2026 - 07:16 nvd
HIGH 8.8

DescriptionCVE.org

A weakness has been identified in TOTOLINK A3700R 9.1.2u.5822_B20200513. This affects the function setWiFiEasyGuestCfg of the file /cgi-bin/cstecgi.cgi. Executing a manipulation of the argument ssid can lead to buffer overflow. The attack may be launched remotely. The exploit has been made available to the public and could be used for attacks.

Executive ViewAI

Why It Matters

Organizations using A weakness face significant risk from CVE-2026-1143, a buffer overflow vulnerability rated CVSS 8.8. Exploitation could allow attackers to corrupt memory, crash the application, or potentially execute arbitrary code. 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.

Business Impact: Severe
Compensating Controls

Apply vendor patch. If immediate patching is not feasible: (1) Implement network-level access controls to limit exposure; (2) Enable enhanced monitoring and alerting; (3) Apply principle of least privilege.

Threat Intelligence Overview

EPSS Score
0.1%
Top 66% exploitable
Exploit
POC
Public exploit code exists
Data Quality
4 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 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
Out-of-Cycle
Exploitation· derived
Poc
System Exposure· derived
Open
Automatable· derived
No
Human Impact
Very High

Priority Score

64
Low Medium High Critical
KEV: 0
EPSS: 0
CVSS: +44
PoC: +20
Weaponized: 0
Threat intel: 0
Gov advisory: 0

Attack Technique

A buffer overflow occurs when a program writes more data to a memory buffer than it was allocated to hold, causing the excess data to spill into adjacent memory regions.

Affected Products (CPE)CVE.org

cpe:2.3:o:totolink:a3700r_firmware:9.1.2u.5822_b20200513:*:*:*:*:*:*:*
CVE-2023-52028 CRITICAL POC
9.8 Jan 11

TOTOlink A3700R v9.1.2u.5822_B20200513 was discovered to contain a remote command execution (RCE) vulnerability via the

CVE-2023-52029 CRITICAL POC
9.8 Jan 11

TOTOlink A3700R v9.1.2u.5822_B20200513 was discovered to contain a remote command execution (RCE) vulnerability via the

CVE-2023-52027 CRITICAL POC
9.8 Jan 11

TOTOlink A3700R v9.1.2u.5822_B20200513 was discovered to contain a remote command execution (RCE) vulnerability via the

CVE-2023-52031 CRITICAL POC
9.8 Jan 11

TOTOlink A3700R v9.1.2u.5822_B20200513 was discovered to contain a remote command execution (RCE) vulnerability via the

CVE-2023-52030 CRITICAL POC
9.8 Jan 11

TOTOlink A3700R v9.1.2u.5822_B20200513 was discovered to contain a remote command execution (RCE) vulnerability via the

CVE-2023-43141 CRITICAL POC
9.8 Sep 25

TOTOLINK A3700R V9.1.2u.6134_B20201202 and N600R V5.3c.5137 are vulnerable to Incorrect Access Control. Rated critical s

CVE-2024-42545 CRITICAL POC
9.8 Aug 12

TOTOLINK A3700R v9.1.2u.5822_B20200513 has a buffer overflow vulnerability in the ssid parameter in setWizardCfg functio

CVE-2024-42543 CRITICAL POC
9.8 Aug 12

TOTOLINK A3700R v9.1.2u.5822_B20200513 has a buffer overflow vulnerability in the http_host parameter in the loginauth f

CVE-2024-37637 CRITICAL POC
9.8 Jun 14

TOTOLINK A3700R V9.1.2u.6165_20211012 was discovered to contain a stack overflow via ssid5g in the function setWizardCfg

CVE-2024-37635 CRITICAL POC
9.8 Jun 13

TOTOLINK A3700R V9.1.2u.6165_20211012 was discovered to contain a stack overflow via ssid in the function setWiFiBasicCf

CVE-2024-37634 CRITICAL POC
9.8 Jun 13

TOTOLINK A3700R V9.1.2u.6165_20211012 was discovered to contain a stack overflow via ssid in the function setWiFiEasyCfg

CVE-2024-37632 CRITICAL POC
9.8 Jun 13

TOTOLINK A3700R V9.1.2u.6165_20211012 was discovered to contain a stack overflow via the password parameter in function

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