CVE-2021-20987 | Hilscher: EtherNet/IP stack crash for specific CIP service

A denial of service and memory corruption vulnerability was found in Hilscher EtherNet/IP Core V2 prior to V2.13.0.21that may lead to code injection through network or make devices crash without recovery.

Published: 2021-02-16 Last update: 2024-11-21 Assigner: [email protected] Source: [email protected]
NVD Status：Modified，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2021-20987 is rated Moderate Risk (54.4/100): CVSS High severity, with medium exploitation likelihood (EPSS 0.37%). 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-2021-20987

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 2025-04-28 0.55% 0.37% -0.18%
2 2025-03-30 0.66% 0.55% -0.11%
3 2025-03-29 — 0.66% —

Full EPSS history (9 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2021-20987

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
8.6 3.1 HIGH
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
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:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:C)
Breaking this can reach past the original component and bite other resources—bigger blast radius.
Confidentiality (C:N)
Doesn’t really leak secrets in a meaningful way.
Integrity (I:N)
Data isn’t meaningfully altered or forged.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
 3.9 4.0 [email protected]
8.6 3.1 HIGH
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
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:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:C)
Breaking this can reach past the original component and bite other resources—bigger blast radius.
Confidentiality (C:N)
Doesn’t really leak secrets in a meaningful way.
Integrity (I:N)
Data isn’t meaningfully altered or forged.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
 3.9 4.0 [email protected]
7.8 2.0 HIGH
AV:N/AC:L/Au:N/C:N/I:N/A:C Click to expand
Access vector (AV:N)
Can be exploited remotely over network reachability.
Access complexity (AC:L)
Exploitation conditions are straightforward and predictable.
Authentication (AU:N)
No authentication is required.
Confidentiality impact (C:N)
No confidentiality impact.
Integrity impact (I:N)
No integrity impact.
Availability impact (A:C)
Complete availability impact.
 10.0 6.9 [email protected]

Weakness enumeration for CVE-2021-20987

Affected software / configurations for CVE-2021-20987

Vendor Product Version Raw CPE
hilscher ethernet\/ip_adapter_firmware >= 2.0, < 2.13.0.21 cpe:2.3:o:hilscher:ethernet\/ip_adapter_firmware:*:*:*:*:*:*:*:*
pepperl-fuchs wcs_firmware <= 1.2.1 cpe:2.3:o:pepperl-fuchs:wcs_firmware:*:*:*:*:*:*:*:*
pepperl-fuchs pxv100-f200-b25-v1d_firmware <= 1.10.0 cpe:2.3:o:pepperl-fuchs:pxv100-f200-b25-v1d_firmware:*:*:*:*:*:*:*:*
pepperl-fuchs pxv100i-f200-b25-v1d_firmware <= 1.10.0 cpe:2.3:o:pepperl-fuchs:pxv100i-f200-b25-v1d_firmware:*:*:*:*:*:*:*:*
pepperl-fuchs pcv100-f200-b25-v1d-6011-6720_firmware <= 1.10.0 cpe:2.3:o:pepperl-fuchs:pcv100-f200-b25-v1d-6011-6720_firmware:*:*:*:*:*:*:*:*
pepperl-fuchs pcv50-f200-b25-v1d_firmware <= 1.10.0 cpe:2.3:o:pepperl-fuchs:pcv50-f200-b25-v1d_firmware:*:*:*:*:*:*:*:*
pepperl-fuchs pcv80-f200-b25-v1d_firmware <= 1.10.0 cpe:2.3:o:pepperl-fuchs:pcv80-f200-b25-v1d_firmware:*:*:*:*:*:*:*:*
pepperl-fuchs pcv100-f200-b25-v1d-6011_firmware <= 1.10.0 cpe:2.3:o:pepperl-fuchs:pcv100-f200-b25-v1d-6011_firmware:*:*:*:*:*:*:*:*

References for CVE-2021-20987

cvelogic Threat Intelligence