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Vulnerability record · CVE-2021-33737 · published 14 September 2021

CVE-2021-33737: Siemens simatic cp 343-1 firmware memory buffer overflow vulnerability

Siemens · Simatic Cp 343 1 Firmware

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.

7.5 CVSS 3.1 High EPSS 1.1% · top 36.9% CWE-119 · Memory buffer overflow
7.5CVSS 3.1 base score, v2 7.8
1.1%EPSS exploitation probability, 30 days
NoNot in CISA KEV
6Affected product versions listed by NVD
2References
17 Jun 2026Last modified by NVD

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.

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

Affected products

6 vulnerable configurations from NVD's CPE data, grouped by vendor and product.

References

LinkTags
https://cert-portal.siemens.com/productcert/pdf/ssa-549234.pdf PatchVendor Advisory
https://cert-portal.siemens.com/productcert/pdf/ssa-549234.pdf PatchVendor Advisory

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Related vulnerabilities

Same products first, then exploited flaws of the same weakness class.

9.7CVE-2015-8214Siemens simatic cp 443-1 firmware permissions and access controls vulnerabilityA vulnerability has been identified in SIMATIC NET CP 342-5 (incl. SIPLUS variants) (All versions), SIMATIC NET CP 343-1 Advanced (incl. SIPLUS varia…EPSS 2.1%8.8CVE-2016-8673Siemens simatic s7 300 cpu firmware cross-site request forgery vulnerabilityA vulnerability has been identified in SIMATIC CP 343-1 Advanced (incl. SIPLUS NET variant) (All versions < V3.0.53), SIMATIC CP 443-1 Advanced (incl…EPSS 1.1%7.5CVE-2023-51440Siemens simatic cp 343-1 firmware vulnerabilityA vulnerability has been identified in SIMATIC CP 343-1 (6GK7343-1EX30-0XE0) (All versions), SIMATIC CP 343-1 Lean (6GK7343-1CX10-0XE0) (All versions…EPSS 0.60%7.5CVE-2022-43716Siemens simatic cp 1242-7 v2 firmware use after free vulnerabilityA vulnerability has been identified in SIMATIC CP 1242-7 V2 (6GK7242-7KX31-0XE0) (All versions < V3.4.29), SIMATIC CP 1243-1 (6GK7243-1BX30-0XE0) (Al…EPSS 0.95%7.5CVE-2022-43767Siemens simatic cp 1242-7 v2 firmware vulnerabilityA vulnerability has been identified in SIMATIC CP 1242-7 V2 (6GK7242-7KX31-0XE0) (All versions < V3.4.29), SIMATIC CP 1243-1 (6GK7243-1BX30-0XE0) (Al…EPSS 0.72%7.5CVE-2022-43768Siemens simatic cp 1242-7 v2 firmware allocation without limits vulnerabilityA vulnerability has been identified in SIMATIC CP 1242-7 V2 (6GK7242-7KX31-0XE0) (All versions < V3.4.29), SIMATIC CP 1243-1 (6GK7243-1BX30-0XE0) (Al…EPSS 0.95%7.5CVE-2019-19301Siemens scalance xc-200 firmware uncontrolled resource consumption vulnerabilityA vulnerability has been identified in SCALANCE X200-4P IRT, SCALANCE X201-3P IRT, SCALANCE X201-3P IRT PRO, SCALANCE X202-2IRT, SCALANCE X202-2P IRT…EPSS 1.4%7.5CVE-2019-13946Siemens dk standard ethernet controller uncontrolled resource consumption vulnerabilityProfinet-IO (PNIO) stack versions prior V06.00 do not properly limit internal resource allocation when multiple legitimate diagnostic package request…EPSS 1.5%

Source: NIST National Vulnerability Database (record CVE-2021-33737), CISA KEV, FIRST EPSS (scores of 2026-09-29). This page is refreshed as NVD updates the record.