NVD / CVE Program· CNA Mitsubishi

CVE-2021-20609: Uncontrolled Resource Consumption vulnerability in Mitsubishi Electric MELSEC iQ-R Series R00/01/02CPU, MELSEC iQ-R Series R04/08/16/32/120(

Noroxi assessment

Priority: Monitor (action score 31/100)

The sources we track (CISA KEV, Exploit-DB, Metasploit, Nuclei, GitHub) show no public exploit code or exploitation in the wild.
Probability of exploitation in the next 30 days: 3.2% (FIRST EPSS); higher than 88.4% of all records.
Anyone who can reach it over the internet can trigger it. No account or password is required. No user action is required. No special conditions are required; it is repeatable.
According to the record, no fixed version is available yet.
Mentioned 1 time in Turkish national cyber security advisories (siberguvenlik.gov.tr).

Low priority for now. Update when a fix is released; follow the vendor's advisory.

Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it

Primary sources: NVD · CVE.org · FIRST EPSS

Uncontrolled Resource Consumption vulnerability in Mitsubishi Electric MELSEC iQ-R Series R00/01/02CPU, MELSEC iQ-R Series R04/08/16/32/120(EN)CPU, MELSEC iQ-R Series R08/16/32/120SFCPU, MELSEC iQ-R Series R08/16/32/120PCPU, MELSEC iQ-R Series R08/16/32/120PSFCPU, MELSEC iQ-R Series R16/32/64MTCPU, MELSEC iQ-R Series R12CCPU-V, MELSEC Q Series Q03UDECPU, MELSEC Q Series Q04/06/10/13/20/26/50/100UDEHCPU, MELSEC Q Series Q03/04/06/13/26UDVCPU, MELSEC Q Series Q04/06/13/26UDPVCPU, MELSEC Q Series Q12DCCPU-V, MELSEC Q Series Q24DHCCPU-V(G), MELSEC Q Series Q24/26DHCCPU-LS, MELSEC Q Series MR-MQ100, MELSEC Q Series Q172/173DCPU-S1, MELSEC Q Series Q172/173DSCPU, MELSEC Q Series Q170MCPU, MELSEC Q Series Q170MSCPU(-S1), MELSEC L Series L02/06/26CPU(-P), MELSEC L Series L26CPU-(P)BT and MELIPC Series MI5122-VW allows a remote unauthenticated attacker to cause a denial-of-service (DoS) condition by sending specially crafted packets. System reset is required for recovery.

HighCVSS 7.5 · v3.1—No exploit No fix recorded

BDU:2021-06168

Published: Dec 1, 2021
Updated: Jun 16, 2026
EPSS: 3.2% · 88th percentile
CWE: CWE-400

Report tools

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Action score

Monitor

Low priority for now.

CVSS: 30 / 40 · 7.5 / 10
CISA KEV: 0 / 30 · Not listed
EPSS: 1 / 30 · 3.2%

CNA vs NVD score

NVD: 7.5
CNA · Mitsubishi: 7.5; agree

The score given by the assigning authority versus NVD’s independent score. A gap means the severity is contested.

Get told when this record changes

Not in KEV: no record of exploitation in the wild
No public exploit code on record
No fixed version yet

If any of these changes, we'll tell you in the daily email digest.

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Noroxi analysis

What does it mean in your environment?

The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.

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Affected systems

Is your version affected?

Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.

ProductVersion

Vendor	Product	CPE
mitsubishi	melsec iq-r r00 cpu firmware	cpe:2.3:o:mitsubishi:melsec_iq-r_r00_cpu_firmware
mitsubishi	melsec iq-r r00 cpu	cpe:2.3:h:mitsubishi:melsec_iq-r_r00_cpu
mitsubishi	melsec iq-r r01 cpu firmware	cpe:2.3:o:mitsubishi:melsec_iq-r_r01_cpu_firmware
mitsubishi	melsec iq-r r01 cpu	cpe:2.3:h:mitsubishi:melsec_iq-r_r01_cpu
mitsubishi	melsec iq-r r02 cpu firmware	cpe:2.3:o:mitsubishi:melsec_iq-r_r02_cpu_firmware
mitsubishi	melsec iq-r r02 cpu	cpe:2.3:h:mitsubishi:melsec_iq-r_r02_cpu
mitsubishi	melsec iq-r r04 cpu firmware	cpe:2.3:o:mitsubishi:melsec_iq-r_r04_cpu_firmware
mitsubishi	melsec iq-r r04 cpu	cpe:2.3:h:mitsubishi:melsec_iq-r_r04_cpu
mitsubishi	melsec iq-r r08 cpu firmware	cpe:2.3:o:mitsubishi:melsec_iq-r_r08_cpu_firmware
mitsubishi	melsec iq-r r08 cpu	cpe:2.3:h:mitsubishi:melsec_iq-r_r08_cpu
mitsubishi	melsec iq-r r120 cpu firmware	cpe:2.3:o:mitsubishi:melsec_iq-r_r120_cpu_firmware
mitsubishi	melsec iq-r r120 cpu	cpe:2.3:h:mitsubishi:melsec_iq-r_r120_cpu

and 98 more

Affected versions

NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.

mitsubishi melipc mi5122-vw firmwareall versions
mitsubishi melsec iq-r r00 cpu firmwareup to 24 inclusive
mitsubishi melsec iq-r r01 cpu firmwareup to 24 inclusive
mitsubishi melsec iq-r r02 cpu firmwareup to 24 inclusive
mitsubishi melsec iq-r r04 cpu firmwareup to 57 inclusive
mitsubishi melsec iq-r r04 pcpu firmwareup to 29 inclusive
mitsubishi melsec iq-r r08 cpu firmwareup to 57 inclusive
mitsubishi melsec iq-r r08 cpu firmwareall versions
mitsubishi melsec iq-r r08 pcpu firmwareup to 29 inclusive
mitsubishi melsec iq-r r08 sfcpu firmwareall versions
mitsubishi melsec iq-r r12 ccpu-v firmwareall versions
mitsubishi melsec iq-r r120 cpu firmwareall versions
mitsubishi melsec iq-r r120 cpu firmwareup to 57 inclusive
mitsubishi melsec iq-r r120 pcpu firmwareup to 29 inclusive
mitsubishi melsec iq-r r120 sfcpu firmwareall versions
mitsubishi melsec iq-r r16 cpu firmwareup to 57 inclusive
mitsubishi melsec iq-r r16 cpu firmwareall versions
mitsubishi melsec iq-r r16 mtcpu firmwareall versions
mitsubishi melsec iq-r r16 pcpu firmwareup to 29 inclusive
mitsubishi melsec iq-r r16 sfcpu firmwareall versions

Versions reported by the vendor

Affected version ranges reported by the assigning authority (Mitsubishi). Independent of NVD's CPE analysis and usually ahead of it.

Mitsubishi Electric Corporation MELIPC Series MI5122-VW
- Firmware versions "05" and prioraffected
Mitsubishi Electric Corporation MELSEC iQ-R Series R00CPU
- Firmware versions "24" and prioraffected
Mitsubishi Electric Corporation MELSEC iQ-R Series R01CPU
- Firmware versions "24" and prioraffected
Mitsubishi Electric Corporation MELSEC iQ-R Series R02CPU
- Firmware versions "24" and prioraffected
Mitsubishi Electric Corporation MELSEC iQ-R Series R04CPU
- Firmware versions "57" and prioraffected
Mitsubishi Electric Corporation MELSEC iQ-R Series R04ENCPU
- Firmware versions "57" and prioraffected
Mitsubishi Electric Corporation MELSEC iQ-R Series R08CPU
- Firmware versions "57" and prioraffected
Mitsubishi Electric Corporation MELSEC iQ-R Series R08ENCPU
- Firmware versions "57" and prioraffected
Mitsubishi Electric Corporation MELSEC iQ-R Series R08PCPU
- Firmware versions "29" and prioraffected
Mitsubishi Electric Corporation MELSEC iQ-R Series R08PSFCPU
- Firmware versions "08" and prioraffected
Mitsubishi Electric Corporation MELSEC iQ-R Series R08SFCPU
- Firmware versions "26" and prioraffected
Mitsubishi Electric Corporation MELSEC iQ-R Series R120CPU
- Firmware versions "57" and prioraffected

Same product

mitsubishi: all records

Other highest-scoring records for the same primary product.

CVE-2022-33324Denial-of-Service Vulnerability in Ethernet port of MELSEC iQ-R, iQ-L Series and MELIPC Series
31Monitor
CVE-2021-20611Improper Input Validation vulnerability in Mitsubishi Electric MELSEC iQ-R Series R00/01/02CPU, MELSEC iQ-R Series R04/08/16/32/120(EN)CPU,
31Monitor
CVE-2021-20610Improper Handling of Length Parameter Inconsistency vulnerability in Mitsubishi Electric MELSEC iQ-R Series R00/01/02CPU, MELSEC iQ-R Series
31Monitor

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

No fix version is recorded for this entry. Check the references for vendor advisories.

Exploit status

No known public exploit

No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

No dated events beyond publication.

No history yet (it accumulates with the daily EPSS job).

Patch and commit links

Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.

No commit or PR link among the references.

Credits

All researchers

Finders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.

No credits in the CNA record.

Variant candidates

Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.

No nightly-computed relations.

Chain candidates

An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.

—

Bug bounty scope

No known public program.

Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).

National notice (Türkiye Cybersecurity Directorate / USOM)

Official security notices citing this record; remediation advice is on the agency's page.

TR-21-0958 · Dec 1, 2021( Mitsubishi Electric Bildirimi)

All national notices →

Technical details

Attack conditions

Anyone who can reach it over the internet can trigger it.
No account or password is required.
No user action is required.
No special conditions are required; it is repeatable.

If successful

Confidentiality: none
Integrity: none
Availability: high · the service can be disrupted

Attack vector: Network
Attack complexity: Low
Privileges required: None
User interaction: None
Scope: Unchanged
Confidentiality impact: None
Integrity impact: None
Availability impact: High

Weakness class (CWE)

CWE-400 · Uncontrolled Resource Consumption

CVSS vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

nvd-primary

Root cause

Code that parses nested structures sets no depth or size limit. A small input can turn into a disproportionate processing load.

The bug in code

The whole CWE-400 class

A representative example of this vulnerability class. Not the vendor's source code; it shows the faulty pattern and its fix.

Vulnerable

1function expand(node) {
2  return node.children.map(expand);
3}

Fixed

1const MAX_DEPTH = 32;
2function expand(node, depth = 0) {
3  if (depth > MAX_DEPTH) throw new Error("too deep");
4  return node.children.map((c) => expand(c, depth + 1));
5}

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

Attack patterns (CAPEC)

ATT&CK techniques

Endpoint Denial of ServiceT1499

Change log

No changes recorded on tracked fields yet. Score, KEV, exploit maturity and fix status changes appear here.

References

jvn.jp/vu/JVNVU94434051/index.html

Show all references (2 more)

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

All records