CVE-2026-19814
Received Received - Intake

Stack-Based Buffer Overflow in TOTOLINK A800R Router

Vulnerability report for CVE-2026-19814, including description, CVSS score, EPSS score, affected products, exploitability, helpful resources, and attack-flow context.

Publication date: 2026-08-14

Last updated on: 2026-08-14

Assigner: VulDB

Description

A vulnerability was detected in TOTOLINK A800R 4.1.2cu.5137_B20200730. Affected is the function setMacQos of the file /cgi-bin/cstecgi.cgi of the component firewall.so. Performing a manipulation of the argument macAddress results in stack-based buffer overflow. It is possible to initiate the attack remotely. The exploit is now public and may be used.

CVSS Scores

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Meta Information

Published
2026-08-14
Last Modified
2026-08-14
Generated
2026-08-14
AI Q&A
2026-08-14
EPSS Evaluated
N/A
NVD
EUVD

Affected Vendors & Products

Showing 1 associated CPE
Vendor Product Version / Range
totolink a800r 4.1.2cu.5137_b20200730

Helpful Resources

Exploitability

CWE
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KEV
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CWE ID Description
CWE-121 A stack-based buffer overflow condition is a condition where the buffer being overwritten is allocated on the stack (i.e., is a local variable or, rarely, a parameter to a function).
CWE-119 The product performs operations on a memory buffer, but it reads from or writes to a memory location outside the buffer's intended boundary. This may result in read or write operations on unexpected memory locations that could be linked to other variables, data structures, or internal program data.

Attack-Flow Graph

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Executive Summary

CVE-2026-19814 is a stack-based buffer overflow in TOTOLINK A800R router firmware version V4.1.2cu.5137_B20200730. The vulnerability exists in the setMacQos function of the firewall.so component. The macAddress parameter is passed to sprintf without bounds checking, allowing an attacker to overflow the stack by sending a crafted HTTP POST request.

Detection Guidance

To detect this vulnerability, check if your TOTOLINK A800R router is running firmware version V4.1.2cu.5137_B20200730. Monitor network traffic for malformed HTTP POST requests targeting /cgi-bin/cstecgi.cgi with the setMacQos function. Use vulnerability scanners that support CVE-2026-19814 detection.

Impact Analysis

This vulnerability can be exploited remotely without authentication. It may lead to arbitrary code execution or denial-of-service conditions on the affected router. Since a proof-of-concept is public, attackers could use it to gain control of the device or disrupt its operations.

Compliance Impact

This vulnerability, a stack-based buffer overflow in TOTOLINK A800R, could lead to unauthorized access or control of the device. For GDPR, it may risk data integrity and confidentiality if exploited. HIPAA compliance could be affected if the device processes protected health information and is compromised.

Mitigation Strategies

Immediately update the TOTOLINK A800R firmware to the latest version. If no update is available, disable remote access to the router's web interface or restrict access to trusted networks. Block suspicious HTTP POST requests to /cgi-bin/cstecgi.cgi at the network perimeter.

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