CVE-2026-19813
Received Received - Intake

Stack-Based Buffer Overflow in TOTOLINK A800R Router

Vulnerability report for CVE-2026-19813, 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 security vulnerability has been detected in TOTOLINK A800R 4.1.2cu.5137_B20200730. This impacts the function setMacFilterRules of the file /cgi-bin/cstecgi.cgi of the component firewall.so. Such manipulation of the argument Comment leads to stack-based buffer overflow. The attack may be performed from remote. The exploit has been disclosed publicly and may be used.

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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-2026-19813 is a stack-based buffer overflow vulnerability in TOTOLINK A800R router firmware version V4.1.2cu.5137_B20200730. It exists in the setMacFilterRules function of the firewall.so component. The issue occurs when the function processes the 'Comment' argument from user requests without proper bounds checking before passing it to the strcat function, leading to a stack overflow.

Detection Guidance

To detect this vulnerability, check if your TOTOLINK A800R router is running firmware version V4.1.2cu.5137_B20200730. You can verify this by logging into the router's admin panel and checking the firmware version under system settings. Additionally, monitor network traffic for unusual HTTP POST requests to the /cgi-bin/cstecgi.cgi endpoint with excessively long 'comment' parameters.

Impact Analysis

This vulnerability can be exploited remotely by sending a crafted HTTP POST request with an overly long 'Comment' parameter. Successful exploitation may allow attackers to execute arbitrary code or cause denial-of-service conditions on the affected router.

Compliance Impact

This vulnerability could lead to unauthorized access or control of network devices, potentially exposing sensitive data. For GDPR, it may result in data breaches requiring notification under Article 33. For HIPAA, it could compromise protected health information if exploited in healthcare networks.

Mitigation Strategies

Immediately update the router's firmware to the latest version provided by TOTOLINK. If no update is available, disable remote access to the router's web interface and restrict access to trusted networks only. Consider replacing the device if the vendor does not provide a patch, as the vulnerability is publicly disclosed and exploitable.

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