HIGH

CVE-2021-34593

Q: What is CVE-2021-34593?

In CODESYS V2 Runtime Toolkit 32 Bit full and PLCWinNT prior to versions V2.4.7.56 unauthenticated crafted invalid requests may result in several denial-of-service conditions. Running PLC programs may be stopped, memory may be leaked, or further communication clients may be blocked from accessing the PLC.

Q: Is CVE-2021-34593 actively exploited?

Active exploitation of CVE-2021-34593 has not been confirmed. Its EPSS score was 2.7% on 2026-10-19, the estimated probability of exploitation in the next 30 days.

Q: What is the CVSS score for CVE-2021-34593?

CVE-2021-34593 has a CVSS v3 base score of 7.5 (HIGH severity).

CVSS v3

7.5

HIGH

EPSS Score

2.7 %

exploit probability, as of 2026-10-19

CISA KEV

known exploited

Exploitation

—

SSVC status

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Affected and fixed versions

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

Full record on NVD

Description

In CODESYS V2 Runtime Toolkit 32 Bit full and PLCWinNT prior to versions V2.4.7.56 unauthenticated crafted invalid requests may result in several denial-of-service conditions. Running PLC programs may be stopped, memory may be leaked, or further communication clients may be blocked from accessing the PLC.

Technical details

Published: 2021-10-26

Frequently asked questions

What is CVE-2021-34593?

Is CVE-2021-34593 actively exploited?

Active exploitation of CVE-2021-34593 has not been confirmed. Its EPSS score was 2.7% on 2026-10-19, the estimated probability of exploitation in the next 30 days.

What is the CVSS score for CVE-2021-34593?

CVE-2021-34593 has a CVSS v3 base score of 7.5 (HIGH severity).

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