CVE-2026-19847
Received Received - Intake

Stack-Based Buffer Overflow in TOTOLINK A800R Firmware

Vulnerability report for CVE-2026-19847, 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 flaw has been discovered in TOTOLINK A800R 4.1.2cu.5137_B20200730. Affected is the function setWiFiWpsConfig of the file /cgi-bin/cstecgi.cgi of the component wps.so. The manipulation of the argument pin results in stack-based buffer overflow. The attack can be launched remotely. The exploit has been released to the public and may be used for attacks.

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-2026-19847 is a stack-based buffer overflow in TOTOLINK A800R router firmware version 4.1.2cu.5137_B20200730. The flaw exists in the setWiFiWpsConfig function of the wps.so library, which processes the 'pin' parameter without proper validation. An attacker can send a maliciously long 'pin' value via a POST request to /cgi-bin/cstecgi.cgi, causing a stack overflow that may lead to arbitrary code execution or system crashes.

Detection Guidance

To detect this vulnerability, check if your TOTOLINK A800R router is running firmware version V4.1.2cu.5137_B20200730. Scan for open ports and services on the router, particularly port 80 or 443 for the web interface. Send a crafted POST request to /cgi-bin/cstecgi.cgi with a long 'pin' parameter to observe abnormal behavior or crashes.

Example command to test: curl -X POST -d '{"pin":"<long_string>"}' http://<router_ip>/cgi-bin/cstecgi.cgi. Monitor system logs for crashes or unexpected behavior.

Impact Analysis

This vulnerability allows remote attackers to execute arbitrary code on the affected router or cause denial of service. An attacker could gain control of the device, intercept network traffic, or use it as a foothold to launch further attacks within the local network. Users with vulnerable devices should update firmware immediately to mitigate risks.

Mitigation Strategies

Immediately update the TOTOLINK A800R router to the latest firmware version if an update is available. If no update exists, disable the WPS feature in the router settings to prevent exploitation. Block external access to the web interface (port 80/443) from untrusted networks. Monitor network traffic for suspicious POST requests to /cgi-bin/cstecgi.cgi.

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