No exploitation reportedFix available

CVE-2021-37204

Q: Is CVE-2021-37204 actively exploited?

Active exploitation of CVE-2021-37204 has not been confirmed. Its EPSS score was 2.2% on 2026-10-22, the estimated probability of exploitation in the next 30 days.

Q: What is the CVSS score for CVE-2021-37204?

CVE-2021-37204 has a CVSS v3 base score of 7.5 (HIGH severity), with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H.

No exploitation reported by the sources we read.

Published2022-02-09
Fixed in4.0
WeaknessCWE-672

Am I affected?

With a domain, we read the version its public headers and pages expose. A distribution build can carry the fix under an older number.

Description

A vulnerability has been identified in SIMATIC Drive Controller family (All versions < V2.9.2), SIMATIC Drive Controller family (All versions >= V2.9.2 < V2.9.4), SIMATIC ET 200SP Open Controller CPU 1515SP PC (incl. SIPLUS variants) (All versions), SIMATIC ET 200SP Open Controller CPU 1515SP PC2 (incl. SIPLUS variants) (All versions < V21.9), SIMATIC ET 200SP Open Controller CPU 1515SP PC2 (incl. SIPLUS variants) (All versions >= V21.9 < V21.9.4), SIMATIC ET 200SP Open Controller CPU 1515SP PC2 Ready4Linux (All versions), SIMATIC S7-1200 CPU family (incl. SIPLUS variants) (All versions < V4.5.0), SIMATIC S7-1200 CPU family (incl. SIPLUS variants) (All versions >= V4.5.0 < V4.5.2), SIMATIC S7-1500 CPU family (incl. related ET200 CPUs and SIPLUS variants) (All versions < V2.9.2), SIMATIC S7-1500 CPU family (incl. related ET200 CPUs and SIPLUS variants) (All versions >= V2.9.2 < V2.9.4), SIMATIC S7-1500 Software Controller (All versions < V21.9), SIMATIC S7-1500 Software Controller (All versions >= V21.9 < V21.9.4), SIMATIC S7-PLCSIM Advanced (All versions < V4.0), SIMATIC S7-PLCSIM Advanced (All versions >= V4.0 < V4.0 SP1), SIPLUS TIM 1531 IRC (All versions < V2.3.6), TIM 1531 IRC (All versions < V2.3.6). An unauthenticated attacker could cause a denial-of-service condition in a PLC when sending specially prepared packet over port 102/tcp. A restart of the affected device is needed to restore normal operations.

Timeline

dates in UTC

2022-02-0916:15CVE publishedNVD

Observed activity

isMalicious corpus · updated 2026-10-23 21:37 UTC

Indicators tagged with this CVE, per day0 indicators over 7 days

Block these indicators

Firewall list (EDL, text): https://api.ismalicious.com/edl/cve/CVE-2021-37204?format=txt
CSV export: https://api.ismalicious.com/edl/cve/CVE-2021-37204?format=csv
TAXII collection of exploited CVEs
The EDL and CSV take an API key on the Pro plan.

Versions per branch

NVD

Siemens simatic s7-plcsim advanced firmwareversion to verify

Branch	Affected	Fixed in	Source
4.0	< 4.0	4.0	NVD
4.0	= 4.0	no fix published	NVD

Siemens simatic drive controller cpu 1504d tf firmwareversion to verify

Branch	Affected	Fixed in	Source
2.9	< 2.9.4	2.9.4	NVD

Siemens simatic drive controller cpu 1507d tf firmwareversion to verify

Branch	Affected	Fixed in	Source
2.9	< 2.9.4	2.9.4	NVD

45 more products in the sources.

as publishedRanges as NVD and OSV publish them; a distribution’s build can be fixed under an older number.

Distribution builds and vendor advisories

Packages from OSV.dev and products from the vendors' CSAF advisories.

version not verifiedVersions not verified: read as OSV.dev and the vendors publish them, not checked against each vendor's release list.

Vendor advisories

ICSA-22-041-01 CISA10 known affected
Siemens SIMATIC Industrial Products (Update A)
SIMATIC Drive Controller family · SIMATIC ET 200SP Open Controller CPU 1515SP PC (incl. SIPLUS variants) · SIMATIC ET 200SP Open Controller CPU 1515SP PC2 (incl. SIPLUS variants) · +7 more

Full record on NVD

Fix

Update Siemens simatic s7-plcsim advanced firmware to 4.0
Vendor fix CISA ICSA-22-041-01 · 2 productsUpdate to V2.3.6 or later version
Vendor fix CISA ICSA-22-041-01 · 2 productsUpdate to V21.9.4 or later version
Vendor fix CISA ICSA-22-041-01 · 2 productsUpdate to V4.5.2 or later version
Vendor fix CISA ICSA-22-041-01 · 2 productsUpdate to V2.9.4 or later version
Vendor fix CISA ICSA-22-041-01 · 2 productsUpdate to V4.0 SP1 or later version
No fix planned, says the vendor CISA ICSA-22-041-01 · 2 productsCurrently no fix is planned

Advisories and patches

cert-portal.siemens.comPatch · Vendor Advisory

Detection

Nuclei template: none so far
Exploit-DB: no entry
Proof-of-concept repositories: none listed

Sources

CISA-ADPSSVC decisionnone2025-04-18
OpenCVESSVC decisionnone—
CNACVSS 3.17.5read 2026-10-23
NVDCVSS 3.17.5read 2026-10-23
NVDCVSS 2.07.1read 2026-10-23
CNAweakness (CWE)CWE-672read 2026-10-23
FIRST EPSSEPSS score2.2 %2026-10-22

Technical details

CVSS v3 Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Published: 2022-02-09
Last Modified: 2026-06-17
NVD status: Modified

Frequently asked questions

What is CVE-2021-37204?

Is CVE-2021-37204 actively exploited?

Active exploitation of CVE-2021-37204 has not been confirmed. Its EPSS score was 2.2% on 2026-10-22, the estimated probability of exploitation in the next 30 days.

What is the CVSS score for CVE-2021-37204?

CVE-2021-37204 has a CVSS v3 base score of 7.5 (HIGH severity), with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H.

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