Live › vulnerability › CVE-2026-120596
A malformed TCP option with a zero length byte sends the Nut/Net TCP parser into an infinite loop in Nut/OS up to version 5.1. A single unauthenticated packet to any open TCP port stops all TCP services until the device is rebooted.
Summary written from the sources below. Check the originals before acting.
First seen by InfraStack 2026-11-02 17:24 UTC. All times on this page are UTC.
Devices running firmware built on Nut/OS (Ethernut/egnite) up to and including 5.1 with the Nut/Net TCP stack are affected; any open TCP port is enough, and no login is needed. Look at embedded boards and appliances built on Ethernut hardware or the Nut/OS RTOS. Devices not reachable over a network, or not using Nut/Net TCP, can skip it.
| Product | Ecosystem | Affected | Fixed in |
|---|---|---|---|
| Nut/OS | vendor | <= 5.1 | – |
Unknown from the sources.
Each row is the first time that source carried this signal. The analyst’s rows are its own findings.
A remotely exploitable denial-of-service vulnerability exists in the TCP options parser of the Nut/Net TCP/IP stack included in Nut/OS, developed by Ethernut/Egnite. Nut/OS releases up to version 5.1 are affected. An unauthenticated attacker can send a single TCP segment containing an unknown TCP option with a length byte of zero to any open TCP port on a vulnerable device. When processed, this malformed option triggers an infinite loop in the function NutTcpInputOptions, permanently blocking the TCP processing thread and rendering all TCP-based services unresponsive until the device is rebooted.
This page as .md · .json · in your agent: get_signal("CVE-2026-120596")
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