CVE-2021-33737

Name: CVE-2021-33737
Creator: NVD / NIST
Published: 2021-09-14T11:15:24.8+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

HIGHCVSS 7.5/10EPSS 1.02%

Last modified Jun 17, 2026

CVE-2021-33737 is a high-severity vulnerability rated 7.5/10 on the CVSS scale. A vulnerability has been identified in SIMATIC CP 343-1 (incl. SIPLUS variants) (All versions), SIMATIC CP 343-1 Advanced (incl. EPSS estimates a 1.02% chance of exploitation in the next 30 days.

Description

A vulnerability has been identified in SIMATIC CP 343-1 (incl. SIPLUS variants) (All versions), SIMATIC CP 343-1 Advanced (incl. SIPLUS variants) (All versions), SIMATIC CP 343-1 ERPC (All versions), SIMATIC CP 343-1 Lean (incl. SIPLUS variants) (All versions), SIMATIC CP 443-1 (All versions < V3.3), SIMATIC CP 443-1 (All versions < V3.3), SIMATIC CP 443-1 Advanced (All versions < V3.3), SIPLUS NET CP 443-1 (All versions < V3.3), SIPLUS NET CP 443-1 Advanced (All versions < V3.3). Sending a specially crafted packet to port 102/tcp of an affected device could cause a denial of service condition. A restart is needed to restore normal operations.

Metrics

CVSS 3.1

7.5/10

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

EPSS Probability

1.02%

59.0th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

CWE-119

Affected Software

Vendor	Product	Versions
Siemens	Simatic Cp 343-1 Firmware	All versions
Siemens	Simatic Cp 343-1 Advanced Firmware	All versions
Siemens	Simatic Cp 343-1 Erpc Firmware	All versions
Siemens	Simatic Cp 343-1 Lean Firmware	All versions
Siemens	Simatic Cp 443-1 Firmware	All versions
Siemens	Simatic Cp 443-1 Advanced Firmware	All versions

References

https://cert-portal.siemens.com/productcert/pdf/ssa-549234.pdfPatch, Vendor Advisory
https://cert-portal.siemens.com/productcert/pdf/ssa-549234.pdfPatch, Vendor Advisory

Timeline

Published: Sep 14, 2021
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2021-33737?

How severe is CVE-2021-33737?

CVE-2021-33737 has a CVSS score of 7.5/10 (HIGH severity). The EPSS model estimates a 1.02% probability of exploitation in the next 30 days.

How do I fix CVE-2021-33737?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2021-33737?

Run a free Strix scan to check your systems for this vulnerability.

Scan your code now

Source: NVD / NIST