CVE-2021-21865

mediumpriority · track · 31EPSS 0.014 · 72 %ileDEEURUUS
grimoire priorityP3 · Track
Exploitable?
—
no known exploitation
Likely / severe?
1.40% (72nd) EPSS
CVSS 6.8 · medium
Is it mine?
17 products
Check your exposure
Who says so?
7 sources
cnnvd · enisa_euvd · fstec_bdu · cisa_csaf_ot

EPSS · scored 2026-10-27

A unsafe deserialization vulnerability exists in the PackageManagement.plugin ExtensionMethods.Clone() functionality of CODESYS GmbH CODESYS Development System 3.5.16. A specially crafted file can lead to arbitrary command execution. An attacker can provide a malicious file to trigger this vulnerability.

01

remediations

Vendor fix, mitigation, or workaround guidance, as published by each source.

A vendor fix is available.

  • FixedPMC programming tool 3.x.xpilz_psirt

    Installation of the software version 3.5.17

  • MitigationFesto Automation Suite <2.8.0.138 installed with CODESYS Development System 3.0festo_psirt

    Starting from Festo Automation Suite version 2.8.0.138, Codesys is no longer bundled with the suite and must be downloaded and installed separately by the customer. To mitigate this vulnerability customers are advised to: Download the latest, patched version of Codesys directly from the official Codesys website. Follow the installation and update instructions provided by Codesys to ensure all security fixes are applied. Regularly monitor Codesys security advisories and apply updates promptly. Maintain the Festo Automation Suite connector up to date by installing FAS updates as released by Festo.

  • MitigationFesto Automation Suite <2.8.0.138 installed with CODESYS Development System 3.5.16.10festo_psirt

    Starting from Festo Automation Suite version 2.8.0.138, Codesys is no longer bundled with the suite and must be downloaded and installed separately by the customer. To mitigate this vulnerability customers are advised to: Download the latest, patched version of Codesys directly from the official Codesys website. Follow the installation and update instructions provided by Codesys to ensure all security fixes are applied. Regularly monitor Codesys security advisories and apply updates promptly. Maintain the Festo Automation Suite connector up to date by installing FAS updates as released by Festo.

  • MitigationPMC programming tool 3.x.xpilz_psirt

    Use a hardware firewall, host-based firewall or comparable measures at network level toprotect against unauthorised network communication with the PC. Use a virus scanner or other measures to protect against malware. Only use CODESYS libraries and archives from trusted sources.

  • MitigationFesto Automation Suite <2.8.0.138 installed with CODESYS Development System 3.0cisa_csaf_ot

    Starting from Festo Automation Suite version 2.8.0.138, Codesys is no longer bundled with the suite and must be downloaded and installed separately by the customer. To mitigate this vulnerability customers are advised to: Download the latest, patched version of Codesys directly from the official Codesys website. Follow the installation and update instructions provided by Codesys to ensure all security fixes are applied. Regularly monitor Codesys security advisories and apply updates promptly. Maintain the Festo Automation Suite connector up to date by installing FAS updates as released by Festo.

  • MitigationFesto Automation Suite <2.8.0.138 installed with CODESYS Development System 3.5.16.10cisa_csaf_ot

    Starting from Festo Automation Suite version 2.8.0.138, Codesys is no longer bundled with the suite and must be downloaded and installed separately by the customer. To mitigate this vulnerability customers are advised to: Download the latest, patched version of Codesys directly from the official Codesys website. Follow the installation and update instructions provided by Codesys to ensure all security fixes are applied. Regularly monitor Codesys security advisories and apply updates promptly. Maintain the Festo Automation Suite connector up to date by installing FAS updates as released by Festo.

02

cvss

Technical severity, 0–10. One row per scoring source.

8.8
010

base score 0–10 · higher = more severe · hover a vector to decode⚠ sources disagree · medium–high · 6.8–8.8

v2.06.8mediumAV:N/AC:M/Au:N/C:P/I:P/A:Pprimary · NVD / NIST USexploitability 8.6 · impact 6.4
v3.17.8highCVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:Hprimary · NVD / NIST USexploitability 1.8 · impact 5.9
v3.08.8highCVSS:3.0/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:Hsecondary · ENISA EU
v3.08.8highCVSS:3.0/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:Hsecondary · talos-cna@cisco.com USexploitability 2.8 · impact 5.9
v3.17.8highCVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:Hsecondary · CISA US
v3.17.1highCVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H/E:Usecondary · CVSS-BT (t0sche)
v3.17.8highCVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:Hsecondary · Pilz PSIRT DE
v3.17.8highCVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:Hsecondary · Festo PSIRT DE
v3.17.8highAV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:Hsecondary · FSTEC (BDU) RU
03

weaknesses

The CWE weakness classes this flaw belongs to.

CWE-502USprimaryCWE-502USCWE-502USCWE-502USCWE-502US
04

affected products (17)

Products and version ranges known to be affected.

05

advisories (3)

Vendor and ecosystem advisories describing this.

  • FSA-202601Several CODESYS vulnerabilities in Festo Automation Suite2026-02-26csaf · festo_psirtDE

    Starting with Festo Automation Suite (FAS) version 2.8.0.138, the suite is delivered only with a connector to Codesys, rather than including Codesys directly. Prior to this version, Codesys was bundled within the FAS installation. From version 2.8.0.138 onwards, customers are required to download and install Codesys independently. This change impacts the handling of security vulnerabilities (CVEs) related to Codesys. Any Codesys-related security issues must now be addressed by the customer through their separate Codesys installation. The FAS itself includes only the connector component, which is maintained and updated within the suite. Please ensure that Codesys is kept up to date independently to mitigate any potential security risks associated with the Codesys software.

  • VDE-2021-061Pilz: PMC programming tool 3.x.x affected by multiple vulnerabilities2022-04-26csaf · pilz_psirtDE

    The software product PMC programming tool from Pilz is based on the software CODESYS Development System from CODESYS GmbH. This software is affected by several vulnerabilities, which an attacker can exploit locally or via the network. This means that, in a worst case, attackers could execute arbitrary program code on the PC on which the PMC programming tool is used.

  • ICSA-26-076-01CODESYS in Festo Automation Suite2026-02-26icsa · cisa_csaf_otUS

    Starting with Festo Automation Suite (FAS) version 2.8.0.138, the suite is delivered only with a connector to Codesys, rather than including Codesys directly. Prior to this version, Codesys was bundled within the FAS installation. From version 2.8.0.138 onwards, customers are required to download and install Codesys independently. This change impacts the handling of security vulnerabilities (CVEs) related to Codesys. Any Codesys-related security issues must now be addressed by the customer through their separate Codesys installation. The FAS itself includes only the connector component, which is maintained and updated within the suite. Please ensure that Codesys is kept up to date independently to mitigate any potential security risks associated with the Codesys software.

06

also known as (5)

Other names and identifiers for this entity.

07

sources

Which sources assert this record, and when.

cnnvdenisa_euvdfstec_bducisa_csaf_otfesto_psirtnvdpilz_psirtNVDCVE.orgMITRE
published 2021-08-02modified 2026-06-17
09

references (9)

External citations — patches, advisories, analysis.

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