CVE-2021-38202Network attack vector

System crash via unterminated NFSD tracepoint name

Published Aug 8, 2021 · Updated May 12, 2026

An out-of-bounds read in all Siemens SIMATIC S7-1500 TM MFP GNU/Linux subsystem versions allows remote attackers to crash it via NFS traffic. The nfs_dirent tracepoint copies a length-delimited directory-entry name, then __assign_str calls strlen on the potentially non-NUL-terminated name. The fault is reachable only while the nfsd trace event framework is enabled; the documented consequence is service interruption, not data access or modification.

CVSS severity7.5
High
EPSS probability3.19%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

An out-of-bounds read in all Siemens SIMATIC S7-1500 TM MFP GNU/Linux subsystem versions allows remote attackers to crash it via NFS traffic. The nfs_dirent tracepoint copies a length-delimited directory-entry name, then __assign_str calls strlen on the potentially non-NUL-terminated name. The fault is reachable only while the nfsd trace event framework is enabled; the documented consequence is service interruption, not data access or modification.

The record

CVE
CVE-2021-38202
Published
Aug 8, 2021
Updated
May 12, 2026
Vendor
Siemens
Product
SIMATIC S7-1500 TM MFP - GNU/Linux subsystem
Classifications
CWE-125, T1499
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Aug 8, 2021CVE publishedPublication date reported by the CVE source.
  2. May 12, 2026Record 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=0 <*

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Siemens · SIMATIC S7-1500 TM MFP - GNU/Linux subsystemversion=0 <*

Published CVSS scores

5.0NIST NVDAV:N/AC:L/Au:N/C:N/I:N/A:P
7.5NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
7.5Siemens ProductCERTCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

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.

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No observations available

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

Weakness, pattern, technique

CWE-125Out-of-bounds Read
T1499Endpoint Denial of Service

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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