CVE-2026-35225: Improper timeout handling in CODESYS EtherNetIP

Severity: high (CVSS 8.7 v4.0)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.4% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-04-23 · updated 2026-10-26
Weakness: CWE-754

Description

An unauthenticated remote attacker is able to exhaust all available TCP connections in the CODESYS EtherNet/IP adapter stack, preventing legitimate clients from establishing new connections.

Affected products

CODESYS EtherNetIP: from 1.0.0.0 before 4.9.0.0 — fixed in 4.9.0.0

How to fix

Upgrade to a fixed version: CODESYS EtherNetIP 4.9.0.0. Check the vendor advisory for mitigations.

References

https://codesys.csaf-tp.certvde.com/.well-known/csaf/white/2026/advisory2026-04_vde-2026-040.json
https://www.certvde.com/en/advisories/VDE-2026-040/

Get alerted when CVE-2026-35225 or the next vulnerability affects your stack