CVE-2021-20986Network attack vector

Remote service interruption via unbounded Read Implicit Requests

Published Feb 16, 2021 · Updated Sep 16, 2024

Resource exhaustion in Hilscher PROFINET IO Device V3 before 3.14.0.7 allows remote attackers to interrupt PROFINET communications. The V3 protocol stack fails to limit resources while processing content-dependent Read Implicit Request services, exhausting its available pool. An unauthenticated network peer can stop acyclic requests, drop established cyclic connections, or make an affected device disappear from the network.

CVSS severity7.5
High
EPSS probability1.04%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Resource exhaustion in Hilscher PROFINET IO Device V3 before 3.14.0.7 allows remote attackers to interrupt PROFINET communications. The V3 protocol stack fails to limit resources while processing content-dependent Read Implicit Request services, exhausting its available pool. An unauthenticated network peer can stop acyclic requests, drop established cyclic connections, or make an affected device disappear from the network.

The record

CVE
CVE-2021-20986
Published
Feb 16, 2021
Updated
Sep 16, 2024
Vendor
Hilscher
Product
PROFINET IO-Device
Classifications
CWE-121, CWE-787, T0814
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Feb 16, 2021CVE publishedPublication date reported by the CVE source.
  2. Sep 16, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

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

  1. Affected versionversion=V3 <V3.14.0.7

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Hilscher · PROFINET IO-Deviceversion=V3 <V3.14.0.7
Pepperl+Fuchs · WCSversion=WCS3B-LS610, WCS3B-LS610H, WCS3B-LS610D, WCS3B-LS610DH, WCS3B-LS610H-OM, WCS3B-LS610DH-OM, WCS3B-LS610D-OM, CS3B-LS610-OM <=V3.0.0
Pepperl+Fuchs · PHAversion=PHA300-F200-B17-V1D, PHA400-F200-B17-V1D, PHA300-F200A-B17-V1D, PHA300-F200-B17-T-V1D, PHA200-F200A-B17-V1D, PHA200-F200-B17-V1D, PHA400-F200A-B17-V1D, PHA300-F200A-B17-T-V1D, PHA600-F200A-B17-V1D, PHA500-F200-B17-V1D, PHA500-F200A-B17-V1D, PHA600-F200-B17-V1D, PHA150-F200A-B17-V1D, PHA200-F200A-B17-T-V1D, PHA150-F200-B17-V1D, PHA800-F200-B17-V1D, PHA400-F200A-B17-T-V1D, PHA500-F200A-B17-T-V1D, PHA700-F200-B17-V1D <=V3.1.5
Pepperl+Fuchs · OHVversion=OHV-F230-B17 <=V1.1.0
Pepperl+Fuchs · OITversion=OIT500-F113-B17-CB <=V1.3.4

Published CVSS scores

5.0NVDAV:N/AC:L/Au:N/C:N/I:N/A:P
7.5CERT@VDECVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
7.5Pepperl+FuchsCVSS:3.0/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.

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)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-121Stack-based Buffer Overflow
CWE-787Out-of-bounds Write
T0814Denial of Service

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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