CVE-2021-34593

What it is

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.

At a glance

Exploitability

Can be exploited over the network without logging in. High risk of service disruption.

Exploit odds

2.7% chance of exploitation in the next 30 days (EPSS).

Fix

A patch, advisory or fixed version is referenced. Upgrade or apply it.

Timeline

1. 2021-10-26 10:15 UTC PublishedDisclosed publicly on CVE.org and NVD
2. 2026-06-17 03:56 UTC Last updatedMost recent change to the record

Why it ranks here

• Exploited in the wild: no, CISA does not list it.
• Exploit odds: 2.7% in the next 30 days (EPSS).
• Severity: 7.5 HIGH (CVSS).
• Fix: a patch or advisory is linked.

Details

Published

2021-10-26 10:15 UTC

Last modified

2026-06-17 03:56 UTC

Exploit probability

2.7% · EPSS, next 30 days

Weakness

CWE-755

Record status

Analyzed

Affected

• Wago 750-8202 Firmware < fw20
• Wago 750-8203 Firmware < fw20
• Wago 750-8204 Firmware < fw20
• Wago 750-8206 Firmware < fw20
• Wago 750-8207 Firmware < fw20
• Wago 750-8208 Firmware < fw20
• Wago 750-8210 Firmware < fw20
• Wago 750-8211 Firmware < fw20

Attack profile CVSS 3.1 · 7.5

Attack vector

Network

Complexity

Low

Privileges needed

None

User interaction

None

Scope

Unchanged

Confidentiality

None

Integrity

None

Availability

High

Is it in your code?

Hand this to your coding agent. It searches your project for the affected products and checks versions. Nothing leaves your machine.

Read https://cve-list.com/agent/cve/CVE-2021-34593.md and follow it. Check whether this project is affected by CVE-2021-34593. Read only. Don't change anything and don't upload my code. Tell me yes, no or not sure, with the file as proof.

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