Security readout for executives and security teams
Plain-English summary
This vulnerability affects many Mitsubishi Electric FA engineering tools used on PCs for industrial automation work. A network attacker could impersonate related industrial equipment and send crafted replies that crash the software. Malicious code execution is described as possible but not reproduced in the provided sources.
Executive priority
Treat this as a high-priority OT workstation exposure issue, especially in plants with Mitsubishi engineering tools on reachable networks. Prioritize inventory, vendor guidance, and network isolation before relying on exploitation assumptions.
Technical view
CVE-2021-20587 is a heap-based buffer overflow (CWE-122) in multiple Mitsubishi Electric FA engineering software products. The attack is remote, unauthenticated, low complexity, and requires spoofed MELSEC, GOT, or FREQROL reply packets. CVSS 3.1 is 7.5 with availability impact as the confirmed outcome.
Likely exposure
Exposure is most likely on engineering workstations running affected Mitsubishi Electric tools that communicate with MELSEC, GOT, or FREQROL environments. Workstations on flat OT networks, shared corporate networks, or reachable by untrusted devices are higher concern.
Exploitation context
The provided bundle does not show CISA KEV listing or active exploitation evidence. The documented attack path is remote and unauthenticated, but the confirmed impact is denial of service. Code execution is noted as possible, not reproduced.
Researcher notes
The source bundle supports DoS impact and possible but unconfirmed code execution. Product coverage is broad, including GX Works, GX Developer, GT Designer, configurators, and related tools. Evidence for exploitation in the wild is not provided.
Mitigation direction
- Inventory Mitsubishi Electric FA engineering software across engineering workstations.
- Compare installed versions against the affected product list.
- Review Mitsubishi Electric advisory 2020-021 for vendor-approved updates or mitigations.
- Restrict engineering workstation communication to trusted OT devices and networks.
- Block untrusted paths that could spoof MELSEC, GOT, or FREQROL replies.
Validation and detection
- Confirm whether any listed products are installed on operational PCs.
- Record exact product names and versions for vulnerability matching.
- Review network reachability between engineering workstations and untrusted systems.
- Check whether segmentation limits spoofed industrial-device replies.
- Document residual exposure where vendor fixes or mitigations are unavailable.
Public sources used
Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.
Conservative CVE-to-ATT&CK context
These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.
ATT&CK lookup starting points
Use these exact CWE pages and searches to review the Glexia ATT&CK library from this CVE's weakness and description context.
CWE-122: Exact CWE lookup
Use the exact CWE identifier as the starting point before reviewing related ATT&CK behavior. Open the exact CWE lookup page first, then review the ATT&CK searches from that MITRE weakness context. This is a Glexia lookup hint, not an official ATT&CK mapping.
Open ATT&CK lookupCVE-2021-20587 mapping review
Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.
Open ATT&CK lookup- Severity
- High
- CVSS
- 7.5 (3.1)
- Known Exploited
- No
- Published
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
CNA and ADP enrichment extracted from CVE v5
These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.
CVSS vector scores
1 official scoreWe collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H3.93.6Primary CVE scoreVulnerability scoring details
Base CVSS 3.1 score
7.5HighVector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Source materials
- CVE List V5 sourceCVE List V5
- https://www.mitsubishielectric.com/psirt/vulnerability/pdf/2020-021_en.pdfCVE reference · vendor-advisory
- https://jvn.jp/vu/JVNVU92330101CVE reference · government-resource
- https://www.cisa.gov/news-events/ics-advisories/icsa-21-049-02CVE reference · government-resource
- https://www.mitsubishielectric.com/en/psirt/vulnerability/pdf/2020-021_en.pdfCVE reference · vendor-advisory, x_transferred
- https://jvn.jp/vu/JVNVU92330101/index.htmlCVE reference · government-resource, x_transferred
- https://us-cert.cisa.gov/ics/advisories/icsa-21-049-02CVE reference · government-resource, x_transferred
Products and packages named in the record
CWE details
CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.
Heap-based Buffer Overflow
Heap-based Buffer Overflow represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.