CVE-2021-20594
CWE-200Published: August 6, 2021· Updated: Jun 17, 2026
Official Description
Exposure of Sensitive Information to an Unauthorized Actor vulnerability in Mitsubishi Electric MELSEC iQ-R series Safety CPU modules R08/16/32/120SFCPU firmware versions "26" and prior and Mitsubishi Electric MELSEC iQ-R series SIL2 Process CPU modules R08/16/32/120PSFCPU firmware versions "11" and prior allows a remote unauthenticated attacker to acquire legitimate user names registered in the module via brute-force attack on user names.
Technical Analysis
CVE-2021-20594 can be exploited remotely over the network without requiring physical or adjacent access, significantly expanding the attack surface for threat actors.
The vulnerability requires no privileges and no user interaction, making it a prime target for automated exploitation campaigns and worm-like propagation.
A successful exploit results in complete confidentiality breach (data exposure), with a CVSS base score of 7.5.
From a weakness classification perspective (CWE-200): Information exposure vulnerabilities leak sensitive data to unauthorized actors.
CVSS v3.1 Vector Breakdown
Affected Vendors & Products
Exploit & PoC Resources
Official Patches & Advisories
All References (6)
Quick Facts
Related CVEs (CWE-200)
Recommended Actions
- →Apply vendor patches immediately
- →Monitor CVE-2021-20594 in threat intel feeds
- →Review IDS/IPS signatures for exploitation attempts