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.
History

Tue, 03 Nov 2026 17:00:00 +0000

Type Values Removed Values Added
First Time appeared Ethernut
Ethernut nut/os
Vendors & Products Ethernut
Ethernut nut/os

Mon, 02 Nov 2026 20:15:00 +0000

Type Values Removed Values Added
Weaknesses CWE-730

Mon, 02 Nov 2026 19:00:00 +0000

Type Values Removed Values Added
Weaknesses CWE-730

Mon, 02 Nov 2026 18:30:00 +0000

Type Values Removed Values Added
Weaknesses CWE-835
Metrics cvssV3_1

{'score': 7.5, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H'}

ssvc

{'options': {'Automatable': 'yes', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}


Mon, 02 Nov 2026 17:15:00 +0000

Type Values Removed Values Added
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.
Title CVE-2026-120596
References

cve-icon MITRE

Status: PUBLISHED

Assigner: certcc

Published: 2026-11-02T17:04:18.611Z

Updated: 2026-11-02T17:17:35.066Z

Reserved: 2026-11-02T16:58:49.331Z

Link: CVE-2026-120596

cve-icon Vulnrichment

Updated: 2026-11-02T17:17:28.470Z

cve-icon NVD

Status : Deferred

Published: 2026-11-02T17:17:40.003

Modified: 2026-11-02T19:35:33.347

Link: CVE-2026-120596

cve-icon Redhat

No data.