Egnite Nut/OS up to 5.1 TCP options parser NutTcpInputOptions infinite loop

CVSS Meta Temp Score
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Current Exploit Price (≈)
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CTI Interest Score
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7.5$0-$5k1.23+

Summaryinfo

A vulnerability classified as critical has been found in Egnite Nut and OS up to 5.1. This issue affects the function NutTcpInputOptions of the component TCP options parser. Performing a manipulation results in infinite loop. This vulnerability is cataloged as CVE-2026-120596. It is possible to initiate the attack remotely. There is no exploit available.

Detailsinfo

A vulnerability classified as critical has been found in Egnite Nut and OS up to 5.1. This affects the function NutTcpInputOptions of the component TCP options parser. The manipulation with an unknown input leads to a infinite loop vulnerability. CWE is classifying the issue as CWE-835. The product contains an iteration or loop with an exit condition that cannot be reached, i.e., an infinite loop. This is going to have an impact on availability. The summary by CVE is:

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.

It is possible to read the advisory at ethernut.de. This vulnerability is uniquely identified as CVE-2026-120596 since 11/02/2026. The exploitability is told to be easy. It is possible to initiate the attack remotely. No form of authentication is needed for exploitation. Technical details of the vulnerability are known, but there is no available exploit. The attack technique deployed by this issue is T1499 according to MITRE ATT&CK.

There is no information about possible countermeasures known. It may be suggested to replace the affected object with an alternative product.

Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.

Productinfo

Vendor

Name

Version

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 7.5
VulDB Meta Temp Score: 7.5

VulDB Base Score: 7.5
VulDB Temp Score: 7.5
VulDB Vector: 🔒
VulDB Reliability: 🔍

ADP CISA Base Score: 7.5
ADP CISA Vector: 🔒

CVSSv2info

AVACAuCIA
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VectorComplexityAuthenticationConfidentialityIntegrityAvailability
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VulDB Base Score: 🔒
VulDB Temp Score: 🔒
VulDB Reliability: 🔍

Exploitinginfo

Class: Infinite loop
CWE: CWE-835 / CWE-404
CAPEC: 🔒
ATT&CK: 🔒

Physical: No
Local: No
Remote: Yes

Availability: 🔒
Status: Not defined
Price Prediction: 🔍
Current Price Estimation: 🔒

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Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Recommended: no mitigation known
Status: 🔍

0-Day Time: 🔒

Timelineinfo

11/02/2026 Advisory disclosed
11/02/2026 +0 days CVE reserved
11/02/2026 +0 days VulDB entry created
11/02/2026 +0 days VulDB entry last update

Sourcesinfo

Advisory: ethernut.de
Status: Not defined

CNA: certcc
CVE: CVE-2026-120596 (🔒)

GCVE (CVE): GCVE-0-2026-120596
GCVE (VulDB): GCVE-100-429939

Entryinfo

Created: 11/02/2026 18:28
Changes: 11/02/2026 18:28 (62)
Complete: 🔍
Cache ID: 216::103

Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.

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