Is CVE-2021-34595 actively exploited?

No active exploitation of CVE-2021-34595 has been confirmed so far. Continue monitoring, as exploit status can change.

Can CVE-2021-34595 be exploited remotely?

Yes. CVE-2021-34595 is exploitable remotely over the network (CVSS attack vector: Network).

What is the CVSS score of CVE-2021-34595?

CVE-2021-34595 has a CVSS score of 8.1 (HIGH).

HOME VULNERABILITIESCVE-2021-34595

HIGH

CVE-2021-34595

CWE-823Published: October 26, 2021· Updated: Jun 17, 2026

8.1

CVSS v3.1

Official Description

A 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 to versions V2.4.7.56, resulting in a denial-of-service condition or local memory overwrite.

NVD Source

Technical Analysis

CVE-2021-34595 can be exploited remotely over the network without requiring physical or adjacent access, significantly expanding the attack surface for threat actors.

Exploitation requires low privileges, which limits the exposure to scenarios where an attacker has already gained initial access.

A successful exploit results in full integrity compromise (data manipulation), availability disruption (denial of service), with a CVSS base score of 8.1.

CVSS v3.1 Vector Breakdown

Exploitability

Attack VectorNetwork

Attack ComplexityLow

Privileges Req.Low

User InteractionNone

ScopeUnchanged

Impact

ConfidentialityNone

IntegrityHigh

AvailabilityHigh

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

Affected Vendors & Products

codesys3 product(s)

codesysplcwinntruntime toolkit

wago54 product(s)

750-823 firmware750-823750-829 firmware750-829750-831 firmware750-831750-832 firmware750-832750-852 firmware750-852750-862 firmware750-862+42

Source: NVD CPE · 57 total CPE entries

Exploit & PoC Resources

NO KNOWN EXPLOITNo public exploit confirmed at this time

Exploit-DB

Offensive Security exploit database

GitHub PoC Search

Community PoC repositories

Rapid7 / Metasploit

Metasploit module search

PacketStorm

Security advisories & exploits

External links open in a new tab. Always verify in a controlled environment before use.

Official Patches & Advisories

ADVISORYhttps://customers.codesys.com/index.php?eID=dumpFile&t=f&f=16878&token=e5644ec405590e66aefa62304cb8632df9fc9e9c&download=

News & Research Mentioning CVE-2021-34595

CODESYS in Festo Automation Suite

CISA Alerts· Mar 17, 2026

View CSAF Summary 3. TECHNICAL DETAILS The following versions of CODESYS in Festo Automation Suite are affected: FESTO Software Festo Automation Suite (versions prior to 2.8.0.138) installed with CODESYS Software CODESYS Development System (3.0) vers:all/* FESTO Software Festo Automation Suite (versions prior to 2.8.0.138) installed with CODESYS Software CODESYS Development System (3.5.16.10) vers:all/* FESTO Software Festo Automation Suite (2.8.0.137) installed with CODESYS Software CODESYS Development System (3.0) vers:all/* FESTO Software Festo Automation Suite (2.8.0.137) installed with CODESYS Software CODESYS Development System (3.5.16.10) vers:all/* CVSS Vendor Equipment Vulnerabilities v3 9.8 FESTO, CODESYS CODESYS in Festo Automation Suite D [xlite_meta score:79 src:CISA Alerts xlite_fp:17fca52d9c8a749f3ecbaf32eff92f14e856489804a56a18cc6c0d7f4acd2a9d]