CVEvulnerability
CVE-2020-27213
7.5 HIGH
Official page ↗
- Status
- Modified
- Published
- 2023-10-10
- Last modified
- 2026-06-17
- Assigner
- [email protected]
- CVSS 3.1 ([email protected])
- 7.5 HIGH — CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
- Weaknesses
- CWE-330
Description
An issue was discovered in Ethernut Nut/OS 5.1. The code that generates Initial Sequence Numbers (ISNs) for TCP connections derives the ISN from an insufficiently random source. As a result, an attacker may be able to determine the ISN of current and future TCP connections and either hijack existing ones or spoof future ones. While the ISN generator seems to adhere to RFC 793 (where a global 32-bit counter is incremented roughly every 4 microseconds), proper ISN generation should aim to follow at least the specifications outlined in RFC 6528.
Affected configurations
• ethernut nut\/os 5.1
Related
Weakness · CWE (1)
- CWE-330 Use of Insufficiently Random Values weakness
References
- http://lists.egnite.de/mailman/listinfo/en-nut-announce Not Applicable
- http://www.ethernut.de/en/download/index.html Release Notes
- https://www.cisa.gov/news-events/ics-advisories/icsa-21-042-01 Third Party Advisory, US Government Resource
- https://www.forescout.com/resources/numberjack-weak-isn-generation-in-embedded-tcpip-stacks/ Exploit, Third Party Advisory
- http://lists.egnite.de/mailman/listinfo/en-nut-announce Not Applicable
- http://www.ethernut.de/en/download/index.html Release Notes
- https://www.cisa.gov/news-events/ics-advisories/icsa-21-042-01 Third Party Advisory, US Government Resource
- https://www.forescout.com/resources/numberjack-weak-isn-generation-in-embedded-tcpip-stacks/ Exploit, Third Party Advisory