Improper Input Validation vulnerability exists in Modicon M241/M251 logic controllers firmware prior to V5.1.9.1 that could cause denial of service when specific crafted requests are sent to the controller over HTTP.

A CWE-345: Insufficient Verification of Data Authenticity vulnerability exists which could allow the attacker to execute malicious code on the Modicon M218, M241, M251, and M258 controllers.

An Insufficiently Protected Credentials issue was discovered in Schneider Electric Modicon PLCs Modicon M241, all firmware versions, and Modicon M251, all firmware versions. Log-in credentials are sent over the network with Base64 encoding leaving them susceptible to sniffing. Sniffed credentials could then be used to log into the web application.

A Use of Insufficiently Random Values issue was discovered in Schneider Electric Modicon PLCs Modicon M241, firmware versions prior to Version 4.0.5.11, and Modicon M251, firmware versions prior to Version 4.0.5.11. The session numbers generated by the web application are lacking randomization and are shared between several users. This may allow a current session to be compromised.