CVE-2021-20594

Exposure of Sensitive Information to an Unauthorized Actor vulnerability in Mitsubishi Electric MELSEC iQ-R series CPU modules (R08/16/32/120SFCPU all versions, R08/16/32/120PSFCPU all versions) allows a remote unauthenticated attacker to acquire legitimate user names registered in the module via brute-force attack on user names.

Source: CVE-2021-20594