CVE-2021-36765

Severity: high (CVSS 7.5 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 1.0% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2021-08-04 · updated 2026-06-17
Weakness: CWE-476

Description

In CODESYS EtherNetIP before 4.1.0.0, specific EtherNet/IP requests may cause a null pointer dereference in the downloaded vulnerable EtherNet/IP stack that is executed by the CODESYS Control runtime system.

Affected products

CODESYS Ethernetip: before 4.1.0.0 — fixed in 4.1.0.0

How to fix

Upgrade to a fixed version: CODESYS Ethernetip 4.1.0.0. Check the vendor advisory for mitigations.

References

https://customers.codesys.com/index.php?eID=dumpFile&t=f&f=16806&token=3b0c51de5a6e35bccbb413ddaaa56551ca5490f6&download=
https://customers.codesys.com/index.php?eID=dumpFile&t=f&f=16806&token=3b0c51de5a6e35bccbb413ddaaa56551ca5490f6&download=

Get alerted when CVE-2021-36765 or the next vulnerability affects your stack