CVE-2021-31893

Local DoS via file buffer overflow

Published Jul 13, 2021 · Updated Aug 3, 2024

Buffer overflow in Siemens SIMATIC PCS 7, SIMATIC PDM, SIMATIC STEP 7, and SINAMICS STARTER allows local users to cause denial of service via crafted files. File handling copies attacker-controlled data without checking destination-buffer size, corrupting memory and potentially enabling code execution. Exploitation requires local access to open or process a malicious file; the documented primary impact is service interruption, with code execution only a potential consequence.

CVSS severity7.8
High
EPSS probability0.56%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Buffer overflow in Siemens SIMATIC PCS 7, SIMATIC PDM, SIMATIC STEP 7, and SINAMICS STARTER allows local users to cause denial of service via crafted files. File handling copies attacker-controlled data without checking destination-buffer size, corrupting memory and potentially enabling code execution. Exploitation requires local access to open or process a malicious file; the documented primary impact is service interruption, with code execution only a potential consequence.

The record

CVE
CVE-2021-31893
Published
Jul 13, 2021
Updated
Aug 3, 2024
Vendor
Siemens
Product
SIMATIC STEP 7
Classifications
CWE-120, T1203
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Jul 13, 2021CVE publishedPublication date reported by the CVE source.
  2. Aug 3, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=All versions < V5.6 SP2 HF3

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

Siemens · SIMATIC STEP 7version=All versions < V5.6 SP2 HF3
Siemens · SIMATIC PDMversion=All versions < V9.2
Siemens · SINAMICS STARTERversion=All versions < V5.4 HF2
Siemens · SIMATIC PCS 7version=All versions; version=All versions < V9.0 SP3

Published CVSS scores

7.8NVDCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
7.2NVDAV:L/AC:L/Au:N/C:C/I:C/A:C

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-120Buffer Copy without Checking Size of Input ('Classic Buffer Overflow')
T1203Exploitation for Client Execution

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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