How severe is CVE-2021-25673?

CVE-2021-25673 has a CVSS 3.x base score of 5.5, rated medium severity. It is exploitable over local access with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.

Is CVE-2021-25673 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (13th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-25673?

CVE-2021-25673 affects Siemens Simatic S7-plcsim. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2021-25673?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.

When was CVE-2021-25673 published?

CVE-2021-25673 was published on 2021-03-15 and last updated on 2026-06-17.

CVE-2021-25673

CVE-2021-25673 is a medium-severity vulnerability in Siemens Simatic S7-plcsim with a CVSS 3.x base score of 5.5. 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-835.

Key facts

Severity: Medium (CVSS 3.x base score 5.5)
CVSS v2: 4.9
EPSS exploit prediction: 0% (13th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-835
Affected product: Siemens Simatic S7-plcsim
Published: 2021-03-15
Last modified: 2026-06-17

Description

A vulnerability has been identified in SIMATIC S7-PLCSIM V5.4 (All versions). An attacker with local access to the system could cause a Denial-of-Service condition in the application when it is used to open a specially crafted file. As a consequence, the application could enter an infinite loop, become unresponsive and must be restarted to restore the service.

Frequently asked questions

What is CVE-2021-25673?: A vulnerability has been identified in SIMATIC S7-PLCSIM V5.4 (All versions). An attacker with local access to the system could cause a Denial-of-Service condition in the application when it is used to open a specially crafted file. As a consequence, the application could enter an infinite loop, become unresponsive and must be restarted to restore the service.
How severe is CVE-2021-25673?: CVE-2021-25673 has a CVSS 3.x base score of 5.5, rated medium severity. It is exploitable over local access with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.
Is CVE-2021-25673 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (13th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-25673?: CVE-2021-25673 affects Siemens Simatic S7-plcsim. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2021-25673?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
When was CVE-2021-25673 published?: CVE-2021-25673 was published on 2021-03-15 and last updated on 2026-06-17.

References

https://cert-portal.siemens.com/productcert/pdf/ssa-256092.pdf

Affected products (1)

cpe:2.3:a:siemens:simatic_s7-plcsim:*:*:*:*:*:*:*:*

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