CVE-2026-19846
Received Received - Intake

Stack-Based Buffer Overflow in TOTOLINK A800R Router

Vulnerability report for CVE-2026-19846, 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 identified in TOTOLINK A800R 4.1.2cu.5137_B20200730. This impacts the function setUrlFilterRules of the file /cgi-bin/cstecgi.cgi of the component firewall.so. The manipulation of the argument url leads to stack-based buffer overflow. The attack can be initiated remotely. The exploit is publicly available and might 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

This vulnerability is a stack-based buffer overflow in TOTOLINK A800R router version 4.1.2cu.5137_B20200730. It occurs in the setUrlFilterRules function of the firewall.so component. The issue is caused by improper handling of the 'url' parameter, which is passed directly to strcpy without validation. This allows remote attackers to trigger a buffer overflow by sending excessively long input.

Detection Guidance

To detect this vulnerability, monitor network traffic for requests to /cgi-bin/cstecgi.cgi with unusually long 'url' parameters. Check firewall logs for stack overflow errors in firewall.so. Use tools like Wireshark to inspect HTTP POST requests targeting the vulnerable endpoint.

Impact Analysis

This vulnerability can allow remote attackers to execute arbitrary code on the affected router. This could lead to unauthorized access, data theft, or disruption of network services. Since the exploit is publicly available, the risk of attacks is higher.

Mitigation Strategies

Immediately update the TOTOLINK A800R firmware to the latest version. Disable remote administration if not required. Block external access to /cgi-bin/cstecgi.cgi via firewall rules. Monitor for unusual network activity or crashes in the firewall.so component.

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