CVE-2021-33737

highpriority · track · 31EPSS 0.011 · 64 %ileDEEUUS

grimoire priorityP2 · Scheduled

Exploitable?

—

no known exploitation

Likely / severe?

1.06% (64th) EPSS

CVSS 7.8 · high

Is it mine?

41 products

Check your exposure

Who says so?

4 sources

cnnvd · enisa_euvd · cisa_csaf_ot · siemens_psirt

EPSS · scored 2026-10-27

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.

remediations

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

A vendor fix is available.

FixedSIMATIC CP 443-1 (6GK7443-1EX30-0XE0)siemens_psirt
Update to V3.3 or later version
https://support.industry.siemens.com/cs/ww/en/view/109817938/
FixedSIMATIC CP 443-1 (6GK7443-1EX30-0XE1)siemens_psirt
Update to V3.3 or later version
https://support.industry.siemens.com/cs/ww/en/view/109817938/
FixedSIMATIC CP 443-1 Advanced (6GK7443-1GX30-0XE0)siemens_psirt
Update to V3.3 or later version
https://support.industry.siemens.com/cs/ww/en/view/109817938/
FixedSIPLUS NET CP 443-1 (6AG1443-1EX30-4XE0)siemens_psirt
Update to V3.3 or later version
https://support.industry.siemens.com/cs/ww/en/view/109817938/
FixedSIPLUS NET CP 443-1 Advanced (6AG1443-1GX30-4XE0)siemens_psirt
Update to V3.3 or later version
https://support.industry.siemens.com/cs/ww/en/view/109817938/
FixedSIMATIC CP 443-1 (6GK7443-1EX30-0XE0)cisa_csaf_ot
Update to V3.3 or later version
https://support.industry.siemens.com/cs/ww/en/view/109817938/
FixedSIMATIC CP 443-1 (6GK7443-1EX30-0XE1)cisa_csaf_ot
Update to V3.3 or later version
https://support.industry.siemens.com/cs/ww/en/view/109817938/
FixedSIMATIC CP 443-1 Advanced (6GK7443-1GX30-0XE0)cisa_csaf_ot
Update to V3.3 or later version
https://support.industry.siemens.com/cs/ww/en/view/109817938/
FixedSIPLUS NET CP 443-1 (6AG1443-1EX30-4XE0)cisa_csaf_ot
Update to V3.3 or later version
https://support.industry.siemens.com/cs/ww/en/view/109817938/
FixedSIPLUS NET CP 443-1 Advanced (6AG1443-1GX30-4XE0)cisa_csaf_ot
Update to V3.3 or later version
https://support.industry.siemens.com/cs/ww/en/view/109817938/
MitigationSIMATIC CP 343-1 (incl. SIPLUS variants)siemens_psirt
Limit access to port 102/tcp to trusted users and systems only
MitigationSIMATIC CP 343-1 Advanced (incl. SIPLUS variants)siemens_psirt
Limit access to port 102/tcp to trusted users and systems only
MitigationSIMATIC CP 343-1 ERPC (6GK7343-1FX00-0XE0)siemens_psirt
Limit access to port 102/tcp to trusted users and systems only
MitigationSIMATIC CP 343-1 Lean (incl. SIPLUS variants)siemens_psirt
Limit access to port 102/tcp to trusted users and systems only
MitigationSIMATIC CP 443-1 (6GK7443-1EX30-0XE0)siemens_psirt
Limit access to port 102/tcp to trusted users and systems only
MitigationSIMATIC CP 443-1 (6GK7443-1EX30-0XE1)siemens_psirt
Limit access to port 102/tcp to trusted users and systems only
MitigationSIMATIC CP 443-1 Advanced (6GK7443-1GX30-0XE0)siemens_psirt
Limit access to port 102/tcp to trusted users and systems only
MitigationSIPLUS NET CP 443-1 (6AG1443-1EX30-4XE0)siemens_psirt
Limit access to port 102/tcp to trusted users and systems only
MitigationSIPLUS NET CP 443-1 Advanced (6AG1443-1GX30-4XE0)siemens_psirt
Limit access to port 102/tcp to trusted users and systems only
MitigationSIMATIC CP 343-1 (incl. SIPLUS variants)cisa_csaf_ot
Limit access to port 102/tcp to trusted users and systems only
MitigationSIMATIC CP 343-1 Advanced (incl. SIPLUS variants)cisa_csaf_ot
Limit access to port 102/tcp to trusted users and systems only
MitigationSIMATIC CP 343-1 ERPC (6GK7343-1FX00-0XE0)cisa_csaf_ot
Limit access to port 102/tcp to trusted users and systems only
MitigationSIMATIC CP 343-1 Lean (incl. SIPLUS variants)cisa_csaf_ot
Limit access to port 102/tcp to trusted users and systems only
MitigationSIMATIC CP 443-1 (6GK7443-1EX30-0XE0)cisa_csaf_ot
Limit access to port 102/tcp to trusted users and systems only
MitigationSIMATIC CP 443-1 (6GK7443-1EX30-0XE1)cisa_csaf_ot
Limit access to port 102/tcp to trusted users and systems only
MitigationSIMATIC CP 443-1 Advanced (6GK7443-1GX30-0XE0)cisa_csaf_ot
Limit access to port 102/tcp to trusted users and systems only
MitigationSIPLUS NET CP 443-1 (6AG1443-1EX30-4XE0)cisa_csaf_ot
Limit access to port 102/tcp to trusted users and systems only
MitigationSIPLUS NET CP 443-1 Advanced (6AG1443-1GX30-4XE0)cisa_csaf_ot
Limit access to port 102/tcp to trusted users and systems only
No fix plannedSIMATIC CP 343-1 (incl. SIPLUS variants)siemens_psirt
Currently no fix is planned
No fix plannedSIMATIC CP 343-1 Advanced (incl. SIPLUS variants)siemens_psirt
Currently no fix is planned
No fix plannedSIMATIC CP 343-1 ERPC (6GK7343-1FX00-0XE0)siemens_psirt
Currently no fix is planned
No fix plannedSIMATIC CP 343-1 Lean (incl. SIPLUS variants)siemens_psirt
Currently no fix is planned
No fix plannedSIMATIC CP 343-1 (incl. SIPLUS variants)cisa_csaf_ot
Currently no fix is planned
No fix plannedSIMATIC CP 343-1 Advanced (incl. SIPLUS variants)cisa_csaf_ot
Currently no fix is planned
No fix plannedSIMATIC CP 343-1 ERPC (6GK7343-1FX00-0XE0)cisa_csaf_ot
Currently no fix is planned
No fix plannedSIMATIC CP 343-1 Lean (incl. SIPLUS variants)cisa_csaf_ot
Currently no fix is planned

cvss

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

7.8

010

base score 0–10 · higher = more severe · hover a vector to decode⚠ sources disagree · medium–high · 6.6–7.8

v2.07.8highAV:N/AC:L/Au:N/C:N/I:N/A:Cprimary · NVD / NIST USexploitability 10 · impact 6.9

v2.06.6mediumAV:N/AC:L/Au:N/C:N/I:N/A:C/E:Usecondary · CVSS-BT (t0sche)

v3.17.5highCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H/E:P/RL:U/RC:Csecondary · CISA US

v3.17.5highCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:Hsecondary · productcert@siemens.com DEexploitability 3.9 · impact 3.6

v3.17.5highCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H/E:P/RL:U/RC:Csecondary · Siemens ProductCERT DE

v3.17.5highCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H/E:P/RL:U/RC:Csecondary · ENISA EU

v3.17.5highCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:Hsecondary · NVD / NIST USexploitability 3.9 · impact 3.6

weaknesses

The CWE weakness classes this flaw belongs to.

CWE-119USCWE-119USCWE-119US

affected products (41)

Products and version ranges known to be affected.

SIMATIC CP 343-1 (incl. SIPLUS variants)all versionscisa_csaf_otUS
SIMATIC CP 343-1 Advanced (incl. SIPLUS variants)all versionscisa_csaf_otUS
SIMATIC CP 343-1 ERPC (6GK7343-1FX00-0XE0)all versionscisa_csaf_otUS
SIMATIC CP 343-1 Lean (incl. SIPLUS variants)all versionscisa_csaf_otUS
SIMATIC CP 443-1 (6GK7443-1EX30-0XE0)all versionscisa_csaf_otUS
SIMATIC CP 443-1 (6GK7443-1EX30-0XE1)all versionscisa_csaf_otUS
SIMATIC CP 443-1 Advanced (6GK7443-1GX30-0XE0)all versionscisa_csaf_otUS
SIPLUS NET CP 443-1 (6AG1443-1EX30-4XE0)all versionscisa_csaf_otUS
SIPLUS NET CP 443-1 Advanced (6AG1443-1GX30-4XE0)all versionscisa_csaf_otUS
Siemens SIMATIC CP 343-1 (incl. SIPLUS variants)≤ vers:all/*cisa_csaf_otUS
Siemens SIMATIC CP 343-1 Advanced (incl. SIPLUS variants)≤ vers:all/*cisa_csaf_otUS
Siemens SIMATIC CP 343-1 ERPC (6GK7343-1FX00-0XE0)≤ vers:all/*cisa_csaf_otUS
Siemens SIMATIC CP 343-1 Lean (incl. SIPLUS variants)≤ vers:all/*cisa_csaf_otUS
Siemens SIMATIC CP 443-1 (6GK7443-1EX30-0XE0)< V3.3cisa_csaf_otUS
Siemens SIMATIC CP 443-1 (6GK7443-1EX30-0XE1)< V3.3cisa_csaf_otUS
Siemens SIMATIC CP 443-1 Advanced (6GK7443-1GX30-0XE0)< V3.3cisa_csaf_otUS
Siemens SIPLUS NET CP 443-1 (6AG1443-1EX30-4XE0)< V3.3cisa_csaf_otUS
Siemens SIPLUS NET CP 443-1 Advanced (6AG1443-1GX30-4XE0)< V3.3cisa_csaf_otUS
Siemens SIMATIC CP 343-1 (incl. SIPLUS variants)≤ All versionsenisa_euvdEU
Siemens SIMATIC CP 343-1 Advanced (incl. SIPLUS variants)≤ All versionsenisa_euvdEU

showing 20 of 41

advisories (2)

Vendor and ecosystem advisories describing this.

SSA-549234SSA-549234: Denial-of-Service Vulnerability in SIMATIC NET CP Modules2021-09-14csaf · siemens_psirtDE
A denial of service vulnerability was identified in different types of Communication Processors. An attacker could exploit this vulnerability causing the device to become un-operational until the device is restarted. Siemens has released updates for several affected products and recommends to update to the latest versions. Siemens recommends specific countermeasures for products where updates are not, or not yet available.
ICSA-21-257-15Siemens SIMATIC NET CP Modules2021-09-14icsa · cisa_csaf_otUS
A denial of service vulnerability was identified in different types of Communication Processors. An attacker could exploit this vulnerability causing the device to become un-operational until the device is restarted. Siemens has released updates for several affected products and recommends to update to the latest versions. Siemens recommends specific countermeasures for products where updates are not, or not yet available.

also known as (3)

Other names and identifiers for this entity.

sources

Which sources assert this record, and when.

cnnvd enisa_euvd cisa_csaf_ot siemens_psirt NVD CVE.org MITRE

published 2021-09-14modified 2026-06-17

references (7)

External citations — patches, advisories, analysis.

scry

Attackers weaponise vulnerabilities like this against internet-exposed services. See what is exposed on your perimeter with a free passive scan.

Free scan