CVE-2021-31894

A vulnerability has been identified in SIMATIC PCS 7 V8.2 and earlier (All versions), SIMATIC PCS 7 V9.X (All versions < V9.1 SP2), SIMATIC PDM (All versions < V9.2 SP2), SIMATIC STEP 7 V5.X (All versions < V5.7), SINAMICS STARTER (containing STEP 7 OEM version) (All versions < V5.4 SP2 HF1). A directory containing metafiles relevant to devices' configurations has write permissions. An attacker could leverage this vulnerability by changing the content of certain metafiles and subsequently manipulate parameters or behavior of devices that would be later configured by the affected software.

Published: 2021-07-13 Last update: 2026-06-16 Assigner: [email protected] Source: [email protected]
NVD Status：Modified，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2021-31894 is rated Moderate Risk (40.1/100): CVSS High severity, with low exploitation likelihood (EPSS 0.23%). Review affected assets and schedule remediation.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Exploit prediction scoring system (EPSS) score for CVE-2021-31894

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-06-15 0.03% 0.23% +0.20%
2 2025-07-13 0.08% 0.03% -0.05%
3 2025-03-17 — 0.08% —

Full EPSS history (8 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2021-31894

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
8.8 3.1 HIGH
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H Click to expand
Attack vector (AV:L)
They already need access on the box, or another person has to do something wrong; it’s not a remote drive-by.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:L)
A normal user session is enough; they don’t have to be admin.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:C)
Breaking this can reach past the original component and bite other resources—bigger blast radius.
Confidentiality (C:H)
Serious risk that confidential data gets exposed in a big way.
Integrity (I:H)
They could widely tamper with or forge data—trust in the data is badly hurt.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
 2.0 6.0 [email protected]
7.2 2.0 HIGH
AV:L/AC:L/Au:N/C:C/I:C/A:C Click to expand
Access vector (AV:L)
Requires local access to the target system.
Access complexity (AC:L)
Exploitation conditions are straightforward and predictable.
Authentication (AU:N)
No authentication is required.
Confidentiality impact (C:C)
Complete confidentiality impact.
Integrity impact (I:C)
Complete integrity impact.
Availability impact (A:C)
Complete availability impact.
 3.9 10.0 [email protected]

Weakness enumeration for CVE-2021-31894

Affected software / configurations for CVE-2021-31894

Vendor Product Version Raw CPE
siemens simatic_pcs_7_firmware <= 8.2 cpe:2.3:o:siemens:simatic_pcs_7_firmware:*:*:*:*:*:*:*:*
siemens simatic_pcs_7_firmware 9.0 cpe:2.3:o:siemens:simatic_pcs_7_firmware:9.0:*:*:*:*:*:*:*
siemens simatic_pdm_firmware — cpe:2.3:o:siemens:simatic_pdm_firmware:-:*:*:*:*:*:*:*
siemens simatic_step_7_firmware >= 5.0, < 5.7 cpe:2.3:o:siemens:simatic_step_7_firmware:*:*:*:*:*:*:*:*
siemens sinamics_starter_firmware < 5.4 cpe:2.3:o:siemens:sinamics_starter_firmware:*:*:*:*:*:*:*:*
siemens sinamics_starter_firmware 5.4 cpe:2.3:o:siemens:sinamics_starter_firmware:5.4:-:*:*:*:*:*:*
siemens sinamics_starter_firmware 5.4 cpe:2.3:o:siemens:sinamics_starter_firmware:5.4:hf1:*:*:*:*:*:*
siemens sinamics_starter_firmware 5.4 cpe:2.3:o:siemens:sinamics_starter_firmware:5.4:hf2:*:*:*:*:*:*
siemens sinamics_starter_firmware 5.4 cpe:2.3:o:siemens:sinamics_starter_firmware:5.4:sp1:*:*:*:*:*:*
siemens sinamics_starter_firmware 5.4 cpe:2.3:o:siemens:sinamics_starter_firmware:5.4:sp1_hf1:*:*:*:*:*:*
siemens sinamics_starter_firmware 5.4 cpe:2.3:o:siemens:sinamics_starter_firmware:5.4:sp2:*:*:*:*:*:*

References for CVE-2021-31894

cvelogic Threat Intelligence