CVE-2021-21863

Arbitrary command execution via unsafe profile deserialization

Published Aug 5, 2021 · Updated Aug 3, 2024

Unsafe deserialization in CODESYS Development System 3.5.16 and 3.5.17 allows attackers to execute commands through a crafted profile file. Profile.FromFile() opens the profile path and passes its file stream directly to BinaryFormatter.Deserialize without validating untrusted serialized objects. Exploitation requires a malicious local profile file and a user action that causes the application to load it, after which code runs in the user's context.

CVSS severity8.8
High
EPSS probability1.21%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Unsafe deserialization in CODESYS Development System 3.5.16 and 3.5.17 allows attackers to execute commands through a crafted profile file. Profile.FromFile() opens the profile path and passes its file stream directly to BinaryFormatter.Deserialize without validating untrusted serialized objects. Exploitation requires a malicious local profile file and a user action that causes the application to load it, after which code runs in the user's context.

The record

CVE
CVE-2021-21863
Published
Aug 5, 2021
Updated
Aug 3, 2024
Vendor
CODESYS GmbH
Product
CODESYS Development System
Classifications
CWE-502, T1203
Attack vector
local
Privileges
unauthenticated

Timeline

How it unfolded

  1. Aug 5, 2021CVE publishedPublication date reported by the CVE source.
  2. Aug 3, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

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

  1. Affected versionversion=CODESYS GmbH CODESYS Development System 3.5.16 ,CODESYS GmbH CODESYS Development System 3.5.17

What conditions does exploitation require?

Attack vectorlocal
Required privilegesunauthenticated

What is affected?

CODESYS GmbH · CODESYS Development Systemversion=CODESYS GmbH CODESYS Development System 3.5.16 ,CODESYS GmbH CODESYS Development System 3.5.17

Published CVSS scores

7.8NIST NVDCVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
6.8NIST NVDAV:N/AC:M/Au:N/C:P/I:P/A:P
8.8Cisco TalosCVSS:3.0/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
8.8CODESYS GmbHCVSS:3.0/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/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.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-502Deserialization of Untrusted Data
T1203Exploitation for Client Execution

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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