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CVE-2020-27632
In SIMATIC MV400 family versions prior to v7.0.6, the ISN generator is initialized with a constant value and has constant increments. An…
High7.5EPSS 2.1%
- Published
- Updated
- Reserved
- Assigned by
- mitre
Description
In SIMATIC MV400 family versions prior to v7.0.6, the ISN generator is initialized with a constant value and has constant increments. An attacker could predict and hijack TCP sessions.
Timeline
ID reserved
By mitre
- 5 months later
· 5 months later
Published
- 3 years later
· 3 years later
Record updated
Changes after publication (a new score, a public exploit, EPSS crossing 1, 10 or 50 %, leaving KEV) are kept since November 2026; earlier ones are not known.
Scores
| Scored by | CVSS | Score | Vector |
|---|---|---|---|
| NVDNVD · Modified | 3.1 | High7.5 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N |
- EPSS (exploitation in 30 days)
- 2.1% · top 18% of all CVEs (7 Nov 2026)
Loading the EPSS history…
The list uses the assigner's score when there is one, then CISA's, then NVD's: High 7.5.
Weakness
- n/a
Affected products
n/a
- affected n/a
References (3)
- https://cert-portal.siemens.com/productcert/pdf/ssa-599268.pdf (opens in a new tab)x_transferred
- https://www.cisa.gov/news-events/ics-advisories/icsa-21-042-01 (opens in a new tab)x_transferred
- https://www.forescout.com/resources/numberjack-weak-isn-generation-in-embedded-tcpip-stacks/ (opens in a new tab)x_transferred
Sources
The same CVE in the primary databases and aggregators, to check against.
- CVE.org record (opens in a new tab)
- CVE List JSON (GitHub) (opens in a new tab)
- NVD (opens in a new tab)
- FIRST EPSS (opens in a new tab)
- OSV.dev (opens in a new tab)
- GitHub Advisories (opens in a new tab)
- CIRCL Vulnerability-Lookup (opens in a new tab)
Badge for a README or a ticket
[](https://trackcve.app/cve/CVE-2020-27632)Record last updated .