CVE-2020-27632

mediumpriority · track · 31OT risk · elevatedstack campaign · NUMBER:JACKEPSS 0.021 · 82 %ileDEEURUUS
grimoire priorityP3 · Track
Exploitable?
—
no known exploitation
Likely / severe?
2.14% (82nd) EPSS
CVSS 5 · medium
Is it mine?
38 products
Check your exposure
Who says so?
5 sources
cnnvd · enisa_euvd · fstec_bdu · cert_bund

EPSS · scored 2026-10-27

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.

01

remediations

Vendor fix, mitigation, or workaround guidance, as published by each source.

A vendor fix is available.

  • FixedCapital VSTARcisa_csaf_ot

    uIP-Contiki-NG has a patch in progress. See general recommendations below until a patch is made available.

  • FixedCycloneTCPcisa_csaf_ot

    uIP-Contiki-NG has a patch in progress. See general recommendations below until a patch is made available.

  • FixedFNETcisa_csaf_ot

    uIP-Contiki-NG has a patch in progress. See general recommendations below until a patch is made available.

  • FixedMPLAB Netcisa_csaf_ot

    uIP-Contiki-NG has a patch in progress. See general recommendations below until a patch is made available.

  • FixedNDKTCPIPcisa_csaf_ot

    uIP-Contiki-NG has a patch in progress. See general recommendations below until a patch is made available.

  • FixedNucleus NET Allcisa_csaf_ot

    uIP-Contiki-NG has a patch in progress. See general recommendations below until a patch is made available.

  • FixedNucleus ReadyStart for ARM MIPS and PPCcisa_csaf_ot

    uIP-Contiki-NG has a patch in progress. See general recommendations below until a patch is made available.

  • FixedNucleus Source Codecisa_csaf_ot

    uIP-Contiki-NG has a patch in progress. See general recommendations below until a patch is made available.

  • FixedNut/Netcisa_csaf_ot

    uIP-Contiki-NG has a patch in progress. See general recommendations below until a patch is made available.

  • FixedpicoTCP (EOL)cisa_csaf_ot

    uIP-Contiki-NG has a patch in progress. See general recommendations below until a patch is made available.

  • FixedpicoTCP-NGcisa_csaf_ot

    uIP-Contiki-NG has a patch in progress. See general recommendations below until a patch is made available.

  • FixeduC/TCP-IP (EOL)cisa_csaf_ot

    uIP-Contiki-NG has a patch in progress. See general recommendations below until a patch is made available.

  • FixeduIP (EOL)cisa_csaf_ot

    uIP-Contiki-NG has a patch in progress. See general recommendations below until a patch is made available.

  • FixeduIP-Contiki-NGcisa_csaf_ot

    uIP-Contiki-NG has a patch in progress. See general recommendations below until a patch is made available.

  • FixeduIP-Contiki-OS (end-of-life [EOL])cisa_csaf_ot

    uIP-Contiki-NG has a patch in progress. See general recommendations below until a patch is made available.

  • FixedSIMATIC MV400 familycisa_csaf_ot

    Update to V7.0.6

  • MitigationCapital VSTARcisa_csaf_ot

    Nut/Net has a patch in progress. See general recommendations below until a patch is made available.

  • MitigationCycloneTCPcisa_csaf_ot

    Nut/Net has a patch in progress. See general recommendations below until a patch is made available.

  • MitigationFNETcisa_csaf_ot

    Nut/Net has a patch in progress. See general recommendations below until a patch is made available.

  • MitigationMPLAB Netcisa_csaf_ot

    Nut/Net has a patch in progress. See general recommendations below until a patch is made available.

  • MitigationNDKTCPIPcisa_csaf_ot

    Nut/Net has a patch in progress. See general recommendations below until a patch is made available.

  • MitigationNucleus NET Allcisa_csaf_ot

    Nut/Net has a patch in progress. See general recommendations below until a patch is made available.

  • MitigationNucleus ReadyStart for ARM MIPS and PPCcisa_csaf_ot

    Nut/Net has a patch in progress. See general recommendations below until a patch is made available.

  • MitigationNucleus Source Codecisa_csaf_ot

    Nut/Net has a patch in progress. See general recommendations below until a patch is made available.

  • MitigationNut/Netcisa_csaf_ot

    Nut/Net has a patch in progress. See general recommendations below until a patch is made available.

  • MitigationpicoTCP (EOL)cisa_csaf_ot

    Nut/Net has a patch in progress. See general recommendations below until a patch is made available.

  • MitigationpicoTCP-NGcisa_csaf_ot

    Nut/Net has a patch in progress. See general recommendations below until a patch is made available.

  • MitigationuC/TCP-IP (EOL)cisa_csaf_ot

    Nut/Net has a patch in progress. See general recommendations below until a patch is made available.

  • MitigationuIP (EOL)cisa_csaf_ot

    Nut/Net has a patch in progress. See general recommendations below until a patch is made available.

  • MitigationuIP-Contiki-NGcisa_csaf_ot

    Nut/Net has a patch in progress. See general recommendations below until a patch is made available.

  • MitigationuIP-Contiki-OS (end-of-life [EOL])cisa_csaf_ot

    Nut/Net has a patch in progress. See general recommendations below until a patch is made available.

02

cvss

Technical severity, 0–10. One row per scoring source.

7.5
010

base score 0–10 · higher = more severe · hover a vector to decode⚠ sources disagree · medium–high · 5–7.5

v2.05mediumAV:N/AC:L/Au:N/C:N/I:P/A:Nprimary · NVD / NIST USexploitability 10 · impact 2.9
v3.17.5highCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:Nprimary · NVD / NIST USexploitability 3.9 · impact 3.6
v3.07.5highCVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:Nsecondary · CISA US
v3.17.5highCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N/E:P/RL:O/RC:Csecondary · CISA US
v3.16.5mediumAV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:Nsecondary · FSTEC (BDU) RU
v3.16.9mediumCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N/E:Usecondary · CVSS-BT (t0sche)
03

weaknesses

The CWE weakness classes this flaw belongs to.

CWE-330USCWE-330US
04

affected products (38)

Products and version ranges known to be affected.

showing 20 of 38
05

advisories (3)

Vendor and ecosystem advisories describing this.

  • WID-SEC-W-2023-1987TCP/IP Stack: Mehrere SchwachstellenDeutsch2021-02-11csaf · cert_bundDE

    Ein entfernter, anonymer Angreifer kann mehrere Schwachstellen in TCP/IP Stack ausnutzen, um beliebigen Programmcode auszuführen, einen Denial-of-Service-Zustand herbeiführen oder Sicherheitsvorkehrungen umgehen.

  • ICSA-21-042-01Multiple Embedded TCP/IP Stacks (Update B)2021-02-11icsa · cisa_csaf_otUS

    Successful exploitation of weak initial sequence numbers (ISN) can be used to hijack or spoof TCP connections, cause denial-of-service conditions, inject malicious data, or bypass authentication.

  • ICSA-21-068-07Siemens TCP Stack of SIMATIC MV4002021-03-09icsa · cisa_csaf_otUS

    As a general security measure, Siemens strongly recommends to protect network access to devices with appropriate mechanisms. In order to operate the devices in a protected IT environment, Siemens recommends to configure the environment according to Siemens' operational guidelines for Industrial Security (Download: https://www.siemens.com/cert/operational-guidelines-industrial-security), and to follow the recommendations in the product manuals.

06

also known as (4)

Other names and identifiers for this entity.

07

sources

Which sources assert this record, and when.

cnnvdenisa_euvdfstec_bducert_bundcisa_csaf_otNVDCVE.orgMITRE
published 2021-03-10modified 2026-06-17
08

references (15)

External citations — patches, advisories, analysis.

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