No exploitation reported

CVE-2021-20586

No exploitation reported by the sources we read.

Published2021-01-29

Am I affected?

With a domain, we read the version its public headers and pages expose. A distribution build can carry the fix under an older number.

Description

Resource management errors vulnerability in a robot controller of MELFA FR Series(controller "CR800-*V*D" of RV-*FR***-D-* all versions, controller "CR800-*HD" of RH-*FRH***-D-* all versions, controller "CR800-*HRD" of RH-*FRHR***-D-* all versions, controller "CR800-*V*R with R16RTCPU" of RV-*FR***-R-* all versions, controller "CR800-*HR with R16RTCPU" of RH-*FRH***-R-* all versions, controller "CR800-*HRR with R16RTCPU" of RH-*FRHR***-R-* all versions, controller "CR800-*V*Q with Q172DSRCPU" of RV-*FR***-Q-* all versions, controller "CR800-*HQ with Q172DSRCPU" of RH-*FRH***-Q-* all versions, controller "CR800-*HRQ with Q172DSRCPU" of RH-*FRHR***-Q-* all versions) and a robot controller of MELFA CR Series(controller "CR800-CVD" of RV-8CRL-D-* all versions, controller "CR800-CHD" of RH-*CRH**-D-* all versions) as well as a cooperative robot ASSISTA(controller "CR800-05VD" of RV-5AS-D-* all versions) allows a remote unauthenticated attacker to cause a DoS of the execution of the robot program and the Ethernet communication by sending a large amount of packets in burst over a short period of time. As a result of DoS, an error may occur. A reset is required to recover it if the error occurs.

Timeline

dates in UTC

2021-01-2915:15CVE publishedNVD

Observed activity

isMalicious corpus · updated 2026-10-23 18:48 UTC

Indicators tagged with this CVE, per day0 indicators over 7 days

Block these indicators

Firewall list (EDL, text): https://api.ismalicious.com/edl/cve/CVE-2021-20586?format=txt
CSV export: https://api.ismalicious.com/edl/cve/CVE-2021-20586?format=csv
TAXII collection of exploited CVEs
The EDL and CSV take an API key on the Pro plan.

Versions per branch

NVD

Mitsubishielectric rh12frh55 firmwareversion to verify

Branch	Affected	Fixed in	Source
—	all versions	no fix published	NVD

Mitsubishielectric rh12frh85 firmwareversion to verify

Branch	Affected	Fixed in	Source
—	all versions	no fix published	NVD

Mitsubishielectric rh12rfh70 firmwareversion to verify

Branch	Affected	Fixed in	Source
—	all versions	no fix published	NVD

30 more products in the sources.

as publishedRanges as NVD and OSV publish them; a distribution’s build can be fixed under an older number.

Distribution builds and vendor advisories

Packages from OSV.dev and products from the vendors' CSAF advisories.

version not verifiedVersions not verified: read as OSV.dev and the vendors publish them, not checked against each vendor's release list.

Vendor advisories

ICSA-21-021-04 CISA3 known affected
Mitsubishi Electric MELFA (Update A)
MELFA FR Series, MELFA CR Series, MELFA ASSISTA - MELFA FR Series · MELFA FR Series, MELFA CR Series, MELFA ASSISTA - MELFA CR Series · MELFA FR Series, MELFA CR Series, MELFA ASSISTA - MELFA ASSISTA

Full record on NVD

Fix

Mitigation from the vendor CISA ICSA-21-021-04 · 3 productsUse a firewall or VPN, etc., to prevent unauthorized access when Internet access is required.
Mitigation from the vendor CISA ICSA-21-021-04 · 3 productsUse within a LAN and block access from untrusted networks and hosts through firewalls.
Mitigation from the vendor CISA ICSA-21-021-04 · 3 productsUse an IP filter function and block access from untrusted networks and hosts. The product models and firmware versions that support the IP filter function are:
Mitigation from the vendor CISA ICSA-21-021-04 · 3 productsMELFA FR Series: firmware Version “C2” or later
Mitigation from the vendor CISA ICSA-21-021-04 · 3 productsMELFA CR Series: firmware Version “C2” or later
Mitigation from the vendor CISA ICSA-21-021-04 · 3 productsMELFA ASSISTA: firmware Version “C2” or later

Advisories and patches

www.mitsubishielectric.comVendor Advisory

Detection

Nuclei template: none so far
Exploit-DB: no entry
Proof-of-concept repositories: none listed

Sources

NVDCVSS 3.17.5read 2026-10-23
NVDCVSS 2.07.8read 2026-10-23
FIRST EPSSEPSS score2.7 %2026-10-22

Technical details

CVSS v3 Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Published: 2021-01-29
Last Modified: 2026-06-17
NVD status: Modified

Frequently asked questions

What is CVE-2021-20586?

Is CVE-2021-20586 actively exploited?

Active exploitation of CVE-2021-20586 has not been confirmed. Its EPSS score was 2.7% on 2026-10-22, the estimated probability of exploitation in the next 30 days.

What is the CVSS score for CVE-2021-20586?

CVE-2021-20586 has a CVSS v3 base score of 7.5 (HIGH severity), with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H.

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