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CVE-2020-5652· NVD / CVE Program· CNA jpcert

Uncontrolled resource consumption vulnerability in Ethernet Port on MELSEC iQ-R, Q and L series CPU modules (R 00/01/02 CPU firmware version

Uncontrolled resource consumption vulnerability in Ethernet Port on MELSEC iQ-R, Q and L series CPU modules (R 00/01/02 CPU firmware versions '20' and earlier, R 04/08/16/32/120 (EN) CPU firmware versions '52' and earlier, R 08/16/32/120 SFCPU firmware versions '22' and earlier, R 08/16/32/120 PCPU all versions, R 08/16/32/120 PSFCPU all versions, R 16/32/64 MTCPU all versions, Q03 UDECPU, Q 04/06/10/13/20/26/50/100 UDEHCPU serial number '22081' and earlier , Q 03/04/06/13/26 UDVCPU serial number '22031' and earlier, Q 04/06/13/26 UDPVCPU serial number '22031' and earlier, Q 172/173 DCPU all versions, Q 172/173 DSCPU all versions, Q 170 MCPU all versions, Q 170 MSCPU all versions, L 02/06/26 CPU (-P) and L 26 CPU - (P) BT all versions) allows a remote unauthenticated attacker to stop the Ethernet communication functions of the products via a specially crafted packet, which may lead to a denial of service (DoS) condition .

HighCVSS 7.5 · v3.1—No exploit No fix recorded
Published
Nov 2, 2020
Updated
Jun 16, 2026
EPSS
3.6% · 89th percentile
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Report tools

JSON

Action score

31

Monitor

Low priority for now.

CVSS
30 / 40 · 7.5 / 10
CISA KEV
0 / 30 · Not listed
EPSS
1 / 30 · 3.6%

Affected systems

VendorProduct
mitsubishielectricmelsec q-q04udpvcpu firmware
mitsubishielectricmelsec q-q04udpvcpu
mitsubishielectricmelsec q-q06udpvcpu firmware
mitsubishielectricmelsec q-q06udpvcpu
mitsubishielectricmelsec q-q13udpvcpu firmware
mitsubishielectricmelsec q-q13udpvcpu
mitsubishielectricmelsec q-q26udpvcpu firmware
mitsubishielectricmelsec q-q26udpvcpu
mitsubishielectricmelsec q-q03udvcpu firmware
mitsubishielectricmelsec q-q03udvcpu
mitsubishielectricmelsec q-q04udvcpu firmware
mitsubishielectricmelsec q-q04udvcpu

and 90 more

Affected versions

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

  • mitsubishielectric melsec iq-r00cpu firmware20
  • mitsubishielectric melsec iq-r01cpu firmware20
  • mitsubishielectric melsec iq-r02cpu firmware20
  • mitsubishielectric melsec iq-r04encpu firmware52
  • mitsubishielectric melsec iq-r08encpu firmware52
  • mitsubishielectric melsec iq-r08pcpu firmwareall versions
  • mitsubishielectric melsec iq-r08psfcpu firmwareall versions
  • mitsubishielectric melsec iq-r08sfcpu firmware22
  • mitsubishielectric melsec iq-r120encpu firmware52
  • mitsubishielectric melsec iq-r120pcpu firmwareall versions
  • mitsubishielectric melsec iq-r120psfcpu firmwareall versions
  • mitsubishielectric melsec iq-r120sfcpu firmware22
  • mitsubishielectric melsec iq-r16encpu firmware52
  • mitsubishielectric melsec iq-r16mtcpu firmwareall versions
  • mitsubishielectric melsec iq-r16pcpu firmwareall versions
  • mitsubishielectric melsec iq-r16psfcpu firmwareall versions
  • mitsubishielectric melsec iq-r16sfcpu firmware22
  • mitsubishielectric melsec iq-r32encpu firmware52
  • mitsubishielectric melsec iq-r32mtcpu firmwareall versions
  • mitsubishielectric melsec iq-r32pcpu firmwareall versions

Versions reported by the vendor

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

  • Mitsubishi Electric Corporation MELSEC iQ-R, Q and L series

    • R 00/01/02 CPU firmware versions '20' and earlier, R 04/08/16/32/120 (EN) CPU firmware versions '52' and earlier, R 08/16/32/120 SFCPU firmware versions '22' and earlier, R 08/16/32/120 PCPU all versiaffected

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.

EPSS, last 120 days

FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).

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).

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

ts
function expand(node) {  return node.children.map(expand);}

Fixed

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

Attack context

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

Noroxi analysis

No Noroxi analysis for this record yet

We don't hand-write analysis for all 385,000+ vulnerabilities; that wouldn't be honest. For notable, high-impact vulnerabilities our team writes the mechanism, detection and remediation steps.

We use this product, ask for help

Change log

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

References

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

All records