Is CVE-2026-120596 being exploited?

No public exploit is currently tracked.

How severe is CVE-2026-120596?

CVE-2026-120596 has a CVSS v3 severity of HIGH (7.5).

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CVE-2026-120596

Description

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.