CVE-2021-20586Network attack vector

Unauthenticated service interruption via burst packet exhaustion

Published Jan 29, 2021 · Updated Aug 3, 2024

Resource exhaustion in all Mitsubishi Electric MELFA FR, CR, and ASSISTA controllers allows remote attackers to halt robot programs. The controller's network packet handling exhausts an undisclosed resource when it processes a short, high-volume packet burst. No authentication is required; the resulting error interrupts Ethernet communication and persists until the controller is power-cycled.

CVSS severity7.5
High
EPSS probability2.74%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
Coverage for this vulnerability

See if you're affected

Explore vulnerability checks for your environment with Hinoki.

Book a demo

Summary

What happened

Resource exhaustion in all Mitsubishi Electric MELFA FR, CR, and ASSISTA controllers allows remote attackers to halt robot programs. The controller's network packet handling exhausts an undisclosed resource when it processes a short, high-volume packet burst. No authentication is required; the resulting error interrupts Ethernet communication and persists until the controller is power-cycled.

The record

CVE
CVE-2021-20586
Published
Jan 29, 2021
Updated
Aug 3, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-399, T0814
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jan 29, 2021CVE publishedPublication date reported by the CVE source.
  2. Aug 3, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

Affected buildAffected product and version details are unavailable.

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

7.5Mitsubishi Electric CorporationCVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
7.8NIST National Vulnerability DatabaseAV:N/AC:L/Au:N/C:N/I:N/A:C
7.5NIST National Vulnerability DatabaseCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-399Resource Management Errors
T0814Denial of Service

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

See the directory against your own environment.

Your stack

Check the software in your environment

Book a demo to see how Hinoki identifies affected software and validates exploitability in your environment.

Book a demo