CVE-2026-71939
Received Received - Intake

Buffer Overflow in DrayTek VigorSwitch via ACL Setup

Publication date: 2026-08-24

Last updated on: 2026-08-24

Assigner: VulnCheck

Description
Multiple DrayTek VigorSwitch models contain a buffer overflow vulnerability in the acl_general_setup Add ACE function. The vulnerability is caused by copying the name field into a fixed-size buffer without length validation. A remote attacker can trigger this vulnerability via crafted input, causing a denial of service or potentially executing arbitrary commands. Exploitation requires valid administrative credentials for the device's web management interface.

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Meta Information

Published
2026-08-24
Last Modified
2026-08-24
Generated
2026-08-24
AI Q&A
2026-08-24
EPSS Evaluated
N/A
NVD
CVE-2026-71939
EUVD
EUVD-2026-64998

Affected Vendors & Products

Showing 1 associated CPE
Vendor Product Version / Range
draytek vigorswitch to (exc)

Helpful Resources

Exploitability

CWE
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KEV
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CWE ID Description
CWE-120 The product copies an input buffer to an output buffer without verifying that the size of the input buffer is less than the size of the output buffer.

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Executive Summary

CVE-2026-71939 is a buffer overflow vulnerability in multiple DrayTek VigorSwitch models. It exists in the acl_general_setup Add ACE function where user input is copied into a fixed-size buffer without length validation. This flaw allows remote attackers with valid administrative credentials to cause a denial of service or potentially execute arbitrary commands by sending crafted input.

Detection Guidance

Detection requires checking firmware versions on DrayTek VigorSwitch devices. Compare installed firmware against DrayTek's security advisory versions. Access the device's web management interface and navigate to system information or firmware details. No specific commands are provided in the resources, but manual inspection of firmware versions is necessary.

Impact Analysis

If exploited, this vulnerability could allow an attacker to crash the device, disrupting network operations. In severe cases, it may enable arbitrary code execution on the affected switch, potentially leading to unauthorized access or control of the device. Exploitation requires valid administrative credentials and access to the web management interface.

Compliance Impact

This vulnerability could impact compliance by exposing sensitive network infrastructure to unauthorized access or disruption. For GDPR, it may lead to unauthorized data access or processing disruptions. For HIPAA, it could compromise network integrity required for protected health information systems. Affected organizations should patch immediately to maintain compliance.

Mitigation Strategies

Immediately update affected DrayTek VigorSwitch devices to the latest firmware versions specified in DrayTek's security advisory. Ensure administrative credentials are strong and not exposed. Restrict access to the web management interface via network segmentation or firewall rules. Monitor for unusual activity.

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