CVE-2021-21865 json
A unsafe deserialization vulnerability exists in the PackageManagement.plugin ExtensionMethods.Clone() functionality of CODESYS GmbH CODESY…
published 2021-08-02 5 y ago modified 2026-06-17 4 mo ago also EUVD-2021-9036
- cvss
- 8.8
- version 3.0, CNA
- cisa kev
- Not listed
- not in CISA's catalog
- epss
- 1.4%
- EPSS 1.4% chance of exploitation in 30 days, percentile 72%
- public exploits
- 0
- none known
Summary
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.
Patch / fix
Vendor advisories
What the vendors themselves say about their products: affected, fixed or not affected, and what to do.
cisa ICSA-26-076-01 updated cvss 7.8
CODESYS in Festo Automation Suite
-
CODESYS Development System 3.0 Festo Automation Suite 2.8.0.137, Festo Automation Suite < 2.8.0.138 CODESYS Development System 3.5.16.10 Festo Automation Suite 2.8.0.137, Festo Automation Suite < 2.8.0.138affected: mitigation
-
Festo Automation Suite 2.8.0.138 CODESYS Development System 3.5.21.20fixed
Facts from CISA's republication of the vendor's own advisory (CSAF); the linked advisory is the authoritative source. CISA notification · csaf
Exploit prediction
1.39% chance of exploitation in the next 30 days, higher than 72% of all scored CVEs (FIRST EPSS, 2026-11-08).
CVSS scores
| assigned by | version | score | vector |
|---|---|---|---|
| CNA | 3.0 | 8.8 | CVSS:3.0/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H |
| NVD | 3.1 | 7.8 | CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H |
| NVD | 2.0 | 6.8 | AV:N/AC:M/Au:N/C:P/I:P/A:P |
Affected products
- n/a CODESYS
Classification
- Weakness
-
- CWE-502 Deserialization of Untrusted Data
References
-
customers.codesys.com
/index.php?eID=dumpFile&t=f&f=16805&token=ee583c498941d9fda86490bca98ff21928eec08a&download=
mitigation, patch, vendor-advisory
-
talosintelligence.com
/vulnerability_reports/TALOS-2021-1301
not-applicable, third-party-advisory
Sources
- CVE List CVE-2021-21865
- NVD CVE-2021-21865
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