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Vulnerability record · CVE-2021-21867 · published 18 August 2021

CVE-2021-21867: Codesys deserialization of untrusted data vulnerability

Codesys · Codesys

An unsafe deserialization vulnerability exists in the ObjectManager.plugin ObjectStream.ProfileByteArray functionality of CODESYS GmbH CODESYS Development System 3.5.16 and 3.5.17. A specially crafted file can lead to arbitrary command execution. An attacker can provide a malicious file to trigger this vulnerability.

7.8 CVSS 3.1 High EPSS 1.6% · top 24.5% CWE-502 · Deserialization of untrusted data
7.8CVSS 3.1 base score, v2 6.8
1.6%EPSS exploitation probability, 30 days
NoNot in CISA KEV
1Affected product versions listed by NVD
4References, 2 tagged exploit
17 Jun 2026Last modified by NVD

Description

An unsafe deserialization vulnerability exists in the ObjectManager.plugin ObjectStream.ProfileByteArray functionality of CODESYS GmbH CODESYS Development System 3.5.16 and 3.5.17. A specially crafted file can lead to arbitrary command execution. An attacker can provide a malicious file to trigger this vulnerability.

CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H

Affected products

1 vulnerable configurations from NVD's CPE data, grouped by vendor and product.

References

LinkTags
https://customers.codesys.com/index.php?eID=dumpFile&t=f&f=16805&token=ee583c498941d9fda86490bca98ff21928eec08a&download MitigationPatchVendor Advisory
https://talosintelligence.com/vulnerability_reports/TALOS-2021-1304 ExploitThird Party Advisory
https://customers.codesys.com/index.php?eID=dumpFile&t=f&f=16805&token=ee583c498941d9fda86490bca98ff21928eec08a&download MitigationPatchVendor Advisory
https://talosintelligence.com/vulnerability_reports/TALOS-2021-1304 ExploitThird Party Advisory

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Related vulnerabilities

Same products first, then exploited flaws of the same weakness class.

9.8CVE-2019-16265Codesys eni server out-of-bounds write vulnerabilityCODESYS V2.3 ENI server up to V3.2.2.24 has a Buffer Overflow.EPSS 1.6%9.1CVE-2021-34584Wago 750-823 firmware vulnerabilityCrafted web server requests can be utilised to read partial stack or heap memory or may trigger a denial-of- service condition due to a crash in the …EPSS 1.1%8.6CVE-2019-13538Codesys cross-site scripting vulnerability3S-Smart Software Solutions GmbH CODESYS V3 Library Manager, all versions prior to 3.5.16.0, allows the system to display active library content with…EPSS 0.85%8.1CVE-2021-34595Wago 750-823 firmware memory buffer overflow vulnerabilityA crafted request with invalid offsets may cause an out-of-bounds read or write access in CODESYS V2 Runtime Toolkit 32 Bit full and PLCWinNT prior t…EPSS 0.88%7.8CVE-2025-41700Codesys deserialization of untrusted data vulnerabilityAn unauthenticated attacker can trick a local user into executing arbitrary code by opening a deliberately manipulated CODESYS project file with a CO…EPSS 0.16%7.8CVE-2021-21869Codesys deserialization of untrusted data vulnerabilityAn unsafe deserialization vulnerability exists in the Engine.plugin ProfileInformation ProfileData functionality of CODESYS GmbH CODESYS Development …EPSS 1.8%7.8CVE-2021-21868Codesys deserialization of untrusted data vulnerabilityAn unsafe deserialization vulnerability exists in the ObjectManager.plugin Project.get_MissingTypes() functionality of CODESYS GmbH CODESYS Developme…EPSS 1.6%7.5CVE-2021-34583Wago 750-8214 firmware heap-based buffer overflow vulnerabilityCrafted web server requests may cause a heap-based buffer overflow and could therefore trigger a denial-of- service condition due to a crash in the C…EPSS 8.4%

Source: NIST National Vulnerability Database (record CVE-2021-21867), CISA KEV, FIRST EPSS (scores of 2026-09-27). This page is refreshed as NVD updates the record.