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.

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-2021-31893 is rated Moderate Risk (46.3/100): CVSS High severity, with low exploitation likelihood (EPSS 0.56%). 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-2021-31893

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 0.16% 0.56% +0.40%
2 2025-12-04 0.13% 0.16% +0.03%
3 2025-11-21 — 0.13% —

Full EPSS history (13 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2021-31893

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
7.8 3.1 HIGH
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/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:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
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.
 1.8 5.9 [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-2021-31893

Affected software / configurations for CVE-2021-31893

Vendor Product Version Raw CPE
siemens simatic_pcs_firmware <= 8.2 cpe:2.3:o:siemens:simatic_pcs_firmware:*:*:*:*:*:*:*:*
siemens simatic_pcs_firmware 9.0 cpe:2.3:o:siemens:simatic_pcs_firmware:9.0:-:*:*:*:*:*:*
siemens simatic_pcs_firmware 9.0 cpe:2.3:o:siemens:simatic_pcs_firmware:9.0:sp1:*:*:*:*:*:*
siemens simatic_pcs_firmware 9.0 cpe:2.3:o:siemens:simatic_pcs_firmware:9.0:sp2:*:*:*:*:*:*
siemens simatic_pdm_firmware < 9.2 cpe:2.3:o:siemens:simatic_pdm_firmware:*:*:*:*:*:*:*:*
siemens simatic_step_7_firmware <= 5.6 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:hotfix_1:*:*:*:*:*:*
siemens sinamics_starter_firmware 5.4 cpe:2.3:o:siemens:sinamics_starter_firmware:5.4:hotfix_2:*:*:*:*:*:*

References for CVE-2021-31893

cvelogic Threat Intelligence