CVE-2021-31894

Severity: high (CVSS 8.8 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.2% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2021-07-13 · updated 2026-06-17
Weakness: CWE-732

Description

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.

Affected products

Siemens Simatic Pcs 7 Firmware: through 8.2; 9.0
Siemens Simatic Pdm Firmware: all versions
Siemens Simatic Step 7 Firmware: from 5.0 before 5.7 — fixed in 5.7
Siemens Sinamics Starter Firmware: before 5.4; 5.4, 5.4-hf1, 5.4-hf2, 5.4-sp1, 5.4-sp1_hf1, 5.4-sp2 — fixed in 5.4

How to fix

Upgrade to a fixed version: Siemens Simatic Step 7 Firmware 5.7; Siemens Sinamics Starter Firmware 5.4. Check the vendor advisory for mitigations.

References

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