High severity7.5NVD Advisory· Published Mar 10, 2021· Updated Jun 17, 2026

CVE-2020-27632

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.

AI Insight

LLM-synthesized narrative grounded in this CVE's description and references.

Affected products

Siemens Foundation/Simatic Mv420 Firmware
cpe:2.3:o:siemens:simatic_mv420_firmware:*:*:*:*:*:*:*:*
Range: <7.0.6
Siemens Foundation/Simatic Mv440 Firmware
cpe:2.3:o:siemens:simatic_mv440_firmware:*:*:*:*:*:*:*:*
Range: <7.0.6
SIMATIC/SIMATIC MV400 familydescription
Siemens Foundation/SIMATIC MV400 familyllm-create
Range: <7.0.6

Patches

Vulnerability mechanics

References

cert-portal.siemens.com/productcert/pdf/ssa-599268.pdfnvdVendor Advisory
www.cisa.gov/news-events/ics-advisories/icsa-21-042-01nvd
www.forescout.com/resources/numberjack-weak-isn-generation-in-embedded-tcpip-stacks/nvd

News mentions

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cvss	0.488
epss	0.001
exploit	0.000
kev	0.000
patch	0.000
ransomware	0.000