How severe is CVE-2021-33721?

CVE-2021-33721 has a CVSS 3.x base score of 7.2, rated high severity. It is exploitable over network with low attack complexity, requires high privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.

Is CVE-2021-33721 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 3% (84th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-33721?

CVE-2021-33721 primarily affects Siemens Sinec Network Management System. In total, 3 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2021-33721?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.

When was CVE-2021-33721 published?

CVE-2021-33721 was published on 2021-08-10 and last updated on 2026-06-17.

CVE-2021-33721

CVE-2021-33721 is a high-severity vulnerability in Siemens Sinec Network Management System with a CVSS 3.x base score of 7.2. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-78.

Key facts

Severity: High (CVSS 3.x base score 7.2)
CVSS v2: 9.0
EPSS exploit prediction: 3% (84th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-78
Affected product: Siemens Sinec Network Management System
Published: 2021-08-10
Last modified: 2026-06-17

Description

A vulnerability has been identified in SINEC NMS (All versions < V1.0 SP2). The affected application incorrectly neutralizes special elements when creating batch operations which could lead to command injection. An authenticated remote attacker with administrative privileges could exploit this vulnerability to execute arbitrary code on the system with system privileges.

Frequently asked questions

What is CVE-2021-33721?: A vulnerability has been identified in SINEC NMS (All versions < V1.0 SP2). The affected application incorrectly neutralizes special elements when creating batch operations which could lead to command injection. An authenticated remote attacker with administrative privileges could exploit this vulnerability to execute arbitrary code on the system with system privileges.
How severe is CVE-2021-33721?: CVE-2021-33721 has a CVSS 3.x base score of 7.2, rated high severity. It is exploitable over network with low attack complexity, requires high privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.
Is CVE-2021-33721 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 3% (84th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-33721?: CVE-2021-33721 primarily affects Siemens Sinec Network Management System. In total, 3 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2021-33721?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
When was CVE-2021-33721 published?: CVE-2021-33721 was published on 2021-08-10 and last updated on 2026-06-17.

References

https://cert-portal.siemens.com/productcert/pdf/ssa-756744.pdf

Affected products (3)

cpe:2.3:a:siemens:sinec_network_management_system:*:*:*:*:*:*:*:*
cpe:2.3:a:siemens:sinec_network_management_system:1.0:-:*:*:*:*:*:*
cpe:2.3:a:siemens:sinec_network_management_system:1.0:sp1:*:*:*:*:*:*

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