What’s Vulnerable › Vulnerabilities
CVE-2021-34593: CODESYS V2 runtime: unauthenticated invalid requests may result in denial-of-service
- Severity: medium (CVSS 5.0 v2.0)
- Exploited in the wild: not listed in CISA KEV
- EPSS: 2.7% probability of exploitation in the next 30 days
- Public exploit or detection template: yes
- Published: 2021-10-26 · updated 2026-06-17
- Weakness: CWE-755
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.
Affected products
- CODESYS PLCWinNT: before 2.4.7.56 — fixed in 2.4.7.56
- CODESYS Runtime Toolkit: before 2.4.7.56 — fixed in 2.4.7.56
- WAGO 750-8202 Firmware: before fw20 — fixed in fw20
- WAGO 750-8203 Firmware: before fw20 — fixed in fw20
- WAGO 750-8204 Firmware: before fw20 — fixed in fw20
- WAGO 750-8206 Firmware: before fw20 — fixed in fw20
- WAGO 750-8207 Firmware: before fw20 — fixed in fw20
- WAGO 750-8208 Firmware: before fw20 — fixed in fw20
- WAGO 750-8210 Firmware: before fw20 — fixed in fw20
- WAGO 750-8211 Firmware: before fw20 — fixed in fw20
- WAGO 750-8212 Firmware: before fw20 — fixed in fw20
- WAGO 750-8213 Firmware: before fw20 — fixed in fw20
- WAGO 750-8214 Firmware: before fw20 — fixed in fw20
- WAGO 750-8216 Firmware: before fw20 — fixed in fw20
- WAGO 750-8217 Firmware: before fw20 — fixed in fw20
How to fix
Upgrade to a fixed version: CODESYS PLCWinNT 2.4.7.56; CODESYS Runtime Toolkit 2.4.7.56; 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; WAGO 750-8212 Firmware fw20; WAGO 750-8213 Firmware fw20. Check the vendor advisory for mitigations.
References
- http://packetstormsecurity.com/files/164716/CODESYS-2.4.7.0-Denial-Of-Service.html
- http://packetstormsecurity.com/files/165874/WAGO-750-8xxx-PLC-Denial-Of-Service-User-Enumeration.html
- http://seclists.org/fulldisclosure/2021/Oct/64
- https://customers.codesys.com/index.php?eID=dumpFile&t=f&f=16877&token=8faab0fc1e069f4edfca5d5aba8146139f67a175&download=
- http://packetstormsecurity.com/files/164716/CODESYS-2.4.7.0-Denial-Of-Service.html
- http://packetstormsecurity.com/files/165874/WAGO-750-8xxx-PLC-Denial-Of-Service-User-Enumeration.html
- http://seclists.org/fulldisclosure/2021/Oct/64
- https://customers.codesys.com/index.php?eID=dumpFile&t=f&f=16877&token=8faab0fc1e069f4edfca5d5aba8146139f67a175&download=
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