CVE-2026-120281
Received Received - Intake

Stack-Based Buffer Overflow in WAVLINK WN536AX6-A V260507 OpenVPN Handler

Vulnerability report for CVE-2026-120281, including description, CVSS score, EPSS score, affected products, exploitability, helpful resources, and attack-flow context.

Publication date: 2026-11-02

Last updated on: 2026-11-02

Assigner: VulDB

Description

A vulnerability was found in WAVLINK WN536AX6-A V260507. This affects the function strcpy of the file /protocol.csp of the component OpenVPN Handler. The manipulation of the argument openvpn_ip results in stack-based buffer overflow. The attack may be launched remotely. The exploit has been made public and could be used. The vendor was contacted early about this disclosure.

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Meta Information

Published
2026-11-02
Last Modified
2026-11-02
Generated
2026-11-02
AI Q&A
2026-11-02
EPSS Evaluated
N/A
NVD

Affected Vendors & Products

Showing 1 associated CPE
Vendor Product Version / Range
WAVLINK WN536AX6-A V260507

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-2026-120281 is a stack-based buffer overflow in WAVLINK WN536AX6-A routers running firmware V260507. It occurs in the openvpn_ser handler of /protocol.csp when the openvpn_ip parameter is copied using an unbounded strcpy() function into a 16-byte stack buffer without length validation. This allows attackers to overwrite the saved return address 264 bytes away, potentially causing crashes or arbitrary code execution with root privileges.

Detection Guidance

To detect this vulnerability, monitor for crashes in the ioos backend process or 500/503 errors from the lighttpd frontend. Check if the openvpn_ip parameter in /protocol.csp requests exceeds 16 bytes. Use network scans to identify WAVLINK WN536AX6-A routers running firmware V260507.

Impact Analysis

An attacker can remotely exploit this vulnerability without authentication due to default passwordless login settings. They can crash the Web backend process (ioos), making all dynamic management interfaces unavailable until manually restarted. The exploit may also allow arbitrary code execution with root privileges, giving full control over the device.

Mitigation Strategies

Immediately update the router firmware to a patched version. Disable remote access to the web interface if not required. Block external requests to /protocol.csp with large openvpn_ip parameters using firewall rules. Restrict network access to trusted devices only.

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