CVE-2020-27213 Details
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.
Metrics
CVSS 4.0 Severity and Vector Strings:
No CVSS 4.0 data is available for this CVE.
CVSS 3.x Severity and Vector Strings:
No data available for CVSS Version 2.0 on this CVE.
CISA-ADP
Assessed Sep 19, 2024References to Advisories, Solutions, and Tools
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| URL | Source(s) | Tag(s) |
|---|---|---|
| http://lists.egnite.de/mailman/listinfo/en-nut-announce | CVE | Not Applicable |
| https://www.cisa.gov/news-events/ics-advisories/icsa-21-042-01 | CVE | Third Party AdvisoryUS Government Resource |
| https://www.forescout.com/resources/numberjack-weak-isn-generation-in-embedded-tcpip-stacks/ | CVE | ExploitThird Party Advisory |
| http://www.ethernut.de/en/download/index.html | CVE | Release Notes |
| http://lists.egnite.de/mailman/listinfo/en-nut-announce | [email protected] | Not Applicable |
| https://www.cisa.gov/news-events/ics-advisories/icsa-21-042-01 | [email protected] | Third Party AdvisoryUS Government Resource |
| https://www.forescout.com/resources/numberjack-weak-isn-generation-in-embedded-tcpip-stacks/ | [email protected] | ExploitThird Party Advisory |
| http://www.ethernut.de/en/download/index.html | [email protected] | Release Notes |
Weakness Enumeration
| CWE-ID | CWE Name | Source |
|---|---|---|
| CWE-330 | Use of Insufficiently Random Values | [email protected] |
Affected Products
| Product | Versions |
|---|---|
| ethernut nut/os | 5.1 |
CPE
Remediation
| |
Change History
5 change records found show changes
| Date | Action | Recorded By |
|---|---|---|
| Jun 17, 2026 | CVE Modified | [email protected] |
| Jun 17, 2026 | CVE Modified | CISA-ADP |
| Nov 21, 2024 | CVE Modified | CVE |
| May 14, 2024 | CVE Modified | [email protected] |
| Oct 27, 2023 | Initial Analysis | [email protected] |