CVE-2026-51656

Deferred Deferred - Pending Action

Incorrect Access Control in TOTOLINK T6 VPN Configuration

Publication date: 2026-08-28

Last updated on: 2026-08-28

Assigner: MITRE

Description

Incorrect access control in the getVpnPassCfg function of TOTOLINK T6 4.1.5cu.748_B20211015 allows unauthenticated attackers to obtain VPN pass-through and WAN ping filter settings via sending a crafted POST request to /cgi-bin/cstecgi.cgi.

CVSS Scores

EPSS Scores

Probability:
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Meta Information

Published

2026-08-28

Last Modified

2026-08-28

Generated

2026-08-29

AI Q&A

2026-08-29

EPSS Evaluated

N/A

NVD

CVE-2026-51656

EUVD

EUVD-2026-67878

Affected Vendors & Products

Vendor	Product	Version / Range
totolink	t6	4.1.5cu.748_b20211015

Helpful Resources

Exploitability

CWE

KEV

CWE ID	Description
CWE-UNKNOWN

Attack-Flow Graph

Executive Summary

This vulnerability is an incorrect access control issue in the getVpnPassCfg function of TOTOLINK T6 firmware version 4.1.5cu.748_B20211015. It allows unauthenticated attackers to retrieve VPN pass-through and WAN ping filter settings by sending a specially crafted POST request to the vulnerable endpoint /cgi-bin/cstecgi.cgi.

Detection Guidance

To detect this vulnerability, monitor network traffic for POST requests to /cgi-bin/cstecgi.cgi with parameters related to VPN pass-through or WAN ping filter settings. Check server logs for unauthorized access attempts to these configurations.

Impact Analysis

An attacker could exploit this to gain unauthorized access to sensitive network configuration details like VPN pass-through settings and WAN ping filter configurations without authentication. This could enable further attacks on the network or expose internal network policies.

Mitigation Strategies

Immediately update the TOTOLINK T6 firmware to the latest version. Disable remote access to the web interface if not required. Restrict access to /cgi-bin/cstecgi.cgi via network firewall rules. Monitor for unusual POST requests targeting this endpoint.

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