How severe is CVE-2021-33728?

CVE-2021-33728 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-2021-33728 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 2% (71st percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-33728?

CVE-2021-33728 primarily affects Siemens Sinec Nms. In total, 4 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2021-33728?

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-2021-33728 published?

CVE-2021-33728 was published on 2021-10-12 and last updated on 2026-06-17.

CVE-2021-33728

CVE-2021-33728 is a high-severity vulnerability in Siemens Sinec Nms 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-502.

Key facts

Severity: High (CVSS 3.x base score 7.2)
CVSS v2: 9.0
EPSS exploit prediction: 2% (71st percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-502
Affected product: Siemens Sinec Nms
Published: 2021-10-12
Last modified: 2026-06-17

Description

A vulnerability has been identified in SINEC NMS (All versions < V1.0 SP2 Update 1). The affected system allows to upload JSON objects that are deserialized to JAVA objects. Due to insecure deserialization of user-supplied content by the affected software, a privileged attacker could exploit this vulnerability by sending a crafted serialized Java object. An exploit could allow the attacker to execute arbitrary code on the device with root privileges.

Frequently asked questions

What is CVE-2021-33728?: A vulnerability has been identified in SINEC NMS (All versions < V1.0 SP2 Update 1). The affected system allows to upload JSON objects that are deserialized to JAVA objects. Due to insecure deserialization of user-supplied content by the affected software, a privileged attacker could exploit this vulnerability by sending a crafted serialized Java object. An exploit could allow the attacker to execute arbitrary code on the device with root privileges.
How severe is CVE-2021-33728?: CVE-2021-33728 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-2021-33728 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 2% (71st percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-33728?: CVE-2021-33728 primarily affects Siemens Sinec Nms. In total, 4 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2021-33728?: 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-2021-33728 published?: CVE-2021-33728 was published on 2021-10-12 and last updated on 2026-06-17.

References

https://cert-portal.siemens.com/productcert/pdf/ssa-163251.pdf

Affected products (4)

cpe:2.3:a:siemens:sinec_nms:*:*:*:*:*:*:*:*
cpe:2.3:a:siemens:sinec_nms:1.0:-:*:*:*:*:*:*
cpe:2.3:a:siemens:sinec_nms:1.0:sp1:*:*:*:*:*:*
cpe:2.3:a:siemens:sinec_nms:1.0:sp2:*:*:*:*:*:*

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