How severe is CVE-2021-31893?

CVE-2021-31893 has a CVSS 3.x base score of 7.8, rated high severity. It is exploitable over local access with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.

Is CVE-2021-31893 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (43rd percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-31893?

CVE-2021-31893 primarily affects Siemens Simatic Pcs Firmware. In total, 10 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2021-31893?

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-2021-31893 published?

CVE-2021-31893 was published on 2021-07-13 and last updated on 2026-06-17.

CVE-2021-31893

CVE-2021-31893 is a high-severity vulnerability in Siemens Simatic Pcs Firmware with a CVSS 3.x base score of 7.8. 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-120.

Key facts

Severity: High (CVSS 3.x base score 7.8)
CVSS v2: 7.2
EPSS exploit prediction: 1% (43rd percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-120
Affected product: Siemens Simatic Pcs Firmware
Published: 2021-07-13
Last modified: 2026-06-17

Description

A vulnerability has been identified in SIMATIC PCS 7 V8.2 and earlier (All versions), SIMATIC PCS 7 V9.0 (All versions < V9.0 SP3), SIMATIC PDM (All versions < V9.2), SIMATIC STEP 7 V5.X (All versions < V5.6 SP2 HF3), SINAMICS STARTER (containing STEP 7 OEM version) (All versions < V5.4 HF2). The affected software contains a buffer overflow vulnerability while handling certain files that could allow a local attacker to trigger a denial-of-service condition or potentially lead to remote code execution.

Frequently asked questions

What is CVE-2021-31893?: A vulnerability has been identified in SIMATIC PCS 7 V8.2 and earlier (All versions), SIMATIC PCS 7 V9.0 (All versions < V9.0 SP3), SIMATIC PDM (All versions < V9.2), SIMATIC STEP 7 V5.X (All versions < V5.6 SP2 HF3), SINAMICS STARTER (containing STEP 7 OEM version) (All versions < V5.4 HF2). The affected software contains a buffer overflow vulnerability while handling certain files that could allow a local attacker to trigger a denial-of-service condition or potentially lead to remote code execution.
How severe is CVE-2021-31893?: CVE-2021-31893 has a CVSS 3.x base score of 7.8, rated high severity. It is exploitable over local access with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.
Is CVE-2021-31893 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (43rd percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-31893?: CVE-2021-31893 primarily affects Siemens Simatic Pcs Firmware. In total, 10 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2021-31893?: 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-2021-31893 published?: CVE-2021-31893 was published on 2021-07-13 and last updated on 2026-06-17.

References

https://cert-portal.siemens.com/productcert/pdf/ssa-641963.pdf

Affected products (10)

cpe:2.3:o:siemens:simatic_pcs_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:siemens:simatic_pcs_firmware:9.0:-:*:*:*:*:*:*
cpe:2.3:o:siemens:simatic_pcs_firmware:9.0:sp1:*:*:*:*:*:*
cpe:2.3:o:siemens:simatic_pcs_firmware:9.0:sp2:*:*:*:*:*:*
cpe:2.3:o:siemens:simatic_pdm_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:siemens:simatic_step_7_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:siemens:sinamics_starter_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:siemens:sinamics_starter_firmware:5.4:-:*:*:*:*:*:*
cpe:2.3:o:siemens:sinamics_starter_firmware:5.4:hotfix_1:*:*:*:*:*:*
cpe:2.3:o:siemens:sinamics_starter_firmware:5.4:hotfix_2:*:*:*:*:*:*

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