Vulnerability in Ethernut / Egnite Gmbh Nut/net Tcp/ip Stack
CVE-2026-120596
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.
Published · last modified .
CVSS v3 metric
CVSS v3 base score 7.5 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H.
EPSS exploit prediction
No EPSS score from FIRST.org yet. New CVEs usually get one within a few days; no score means no signal yet, not low risk. How EPSS works.
Affected products
- Ethernut / Egnite Gmbh Nut/net Tcp/ip Stack — versions Nut/OS 5.1
Weakness classification (CWE)
References
Frequently asked questions
- What is CVE-2026-120596?
- CVE-2026-120596 is a high-severity vulnerability in Ethernut / Egnite Gmbh Nut/net Tcp/ip Stack, classified under Loop with Unreachable Exit Condition (Infinite Loop). CVSS score: 7.5/10. Published 2026-11-02.
- How severe is CVE-2026-120596?
- High severity. CVSS v3 base score is 7.5 out of 10.