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No exploitation reportedFix available

CVE-2021-21866

No exploitation reported by the sources we read.

  • Published2021-08-02
  • WeaknessCWE-502

Am I affected?

With a domain, we read the version its public headers and pages expose. A distribution build can carry the fix under an older number.

Description

A unsafe deserialization vulnerability exists in the ObjectManager.plugin ProfileInformation.ProfileData 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.

Timeline

dates in UTC
  1. 2021-08-0221:15CVE publishedNVD

Versions per branch

NVD
Codesys development system
BranchAffectedFixed in
3.5= 3.5.16.0no fix published
3.5= 3.5.17.0no fix published

as publishedRanges as NVD and OSV publish them; a distribution’s build can be fixed under an older number.

Distribution builds and vendor advisories

Packages from OSV.dev and products from the vendors' CSAF advisories.

version not verifiedVersions not verified: read as OSV.dev and the vendors publish them, not checked against each vendor's release list.

Vendor advisories

  • ICSA-26-076-01 CISA1 product fixed · 4 known affected

    CODESYS in Festo Automation Suite

    Festo Automation Suite <2.8.0.138 installed with CODESYS Development System 3.0 · Festo Automation Suite <2.8.0.138 installed with CODESYS Development System 3.5.16.10 · Festo Automation Suite 2.8.0.137 installed with CODESYS Development System 3.0 · +1 more

Full record on NVD

Fix

  1. Mitigation from the vendor CISA ICSA-26-076-01 · 4 productsStarting 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…

Advisories and patches

Detection

Nuclei template
none so far
ProjectDiscovery
Exploit-DB
no entry
Exploit-DB
Proof of concept
Metasploit modules
none listed
Metasploit Framework

Sources

  • NVDCVSS 3.17.8read 2026-10-23
  • CNACVSS 3.08.8known since 2026-10-23
  • NVDCVSS 2.06.8read 2026-10-23
  • CNAweakness (CWE)CWE-502known since 2026-10-23
  • NVDweakness (CWE)CWE-502read 2026-10-23
  • FIRST EPSSEPSS score1.8 %2026-11-08
  • GitHub Advisoriesadvisory—

Identifiers

Technical details

CVSS v3 Vector
CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
Published
2021-08-02
Last Modified
2026-06-17
NVD status
Modified
GitHub Advisory
GHSA-rf3q-ppf3-vv43

Frequently asked questions

What is CVE-2021-21866?

A unsafe deserialization vulnerability exists in the ObjectManager.plugin ProfileInformation.ProfileData 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.

Is CVE-2021-21866 actively exploited?

Active exploitation of CVE-2021-21866 has not been confirmed. Its EPSS score was 1.8% on 2026-11-08, the estimated probability of exploitation in the next 30 days.

What is the CVSS score for CVE-2021-21866?

CVE-2021-21866 has a CVSS v3 base score of 7.8 (HIGH severity), with vector string CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H.

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