Is CVE-2021-34593 actively exploited?

No active exploitation of CVE-2021-34593 has been confirmed so far. Continue monitoring, as exploit status can change.

Can CVE-2021-34593 be exploited remotely?

Yes. CVE-2021-34593 is exploitable remotely over the network (CVSS attack vector: Network).

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

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

HOME VULNERABILITIESCVE-2021-34593

HIGH

CVE-2021-34593

CWE-755Published: October 26, 2021· Updated: Jun 17, 2026

7.5

CVSS v3.1

Official 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.

NVD Source

Technical Analysis

CVE-2021-34593 can be exploited remotely over the network without requiring physical or adjacent access, significantly expanding the attack surface for threat actors.

The vulnerability requires no privileges and no user interaction, making it a prime target for automated exploitation campaigns and worm-like propagation.

A successful exploit results in availability disruption (denial of service), with a CVSS base score of 7.5.

CVSS v3.1 Vector Breakdown

Exploitability

Attack VectorNetwork

Attack ComplexityLow

Privileges Req.None

User InteractionNone

ScopeUnchanged

Impact

ConfidentialityNone

IntegrityNone

AvailabilityHigh

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

Affected Vendors & Products

codesys2 product(s)

plcwinntruntime toolkit

wago26 product(s)

750-8202 firmware750-8202750-8203 firmware750-8203750-8204 firmware750-8204750-8206 firmware750-8206750-8207 firmware750-8207750-8208 firmware750-8208+14

Source: NVD CPE · 28 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

ADVISORYhttp://packetstormsecurity.com/files/164716/CODESYS-2.4.7.0-Denial-Of-Service.html

ADVISORYhttp://packetstormsecurity.com/files/165874/WAGO-750-8xxx-PLC-Denial-Of-Service-User-Enumeration.html

ADVISORYhttp://seclists.org/fulldisclosure/2021/Oct/64

ADVISORYhttps://customers.codesys.com/index.php?eID=dumpFile&t=f&f=16877&token=8faab0fc1e069f4edfca5d5aba8146139f67a175&download=

ADVISORYhttp://packetstormsecurity.com/files/164716/CODESYS-2.4.7.0-Denial-Of-Service.html

ADVISORYhttp://packetstormsecurity.com/files/165874/WAGO-750-8xxx-PLC-Denial-Of-Service-User-Enumeration.html

ADVISORYhttp://seclists.org/fulldisclosure/2021/Oct/64

ADVISORYhttps://customers.codesys.com/index.php?eID=dumpFile&t=f&f=16877&token=8faab0fc1e069f4edfca5d5aba8146139f67a175&download=

News & Research Mentioning CVE-2021-34593

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]