Improper Neutralization of CRLF Sequences in HTTP Headers ('HTTP Response Splitting') vulnerability exists in the embedded web servers in all Modicon M340, Premium, Quantum PLCs and BMXNOR0200 where a denial of service can occur for ~1 minute by sending a specially crafted HTTP request.
https://www.tenable.com/security/research/tra-2018-38
https://www.schneider-electric.com/en/download/document/SEVD-2018-327-01/