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NVD / CVE Program· CNA Mitsubishi

CVE-2022-40267: Authentication Bypass Vulnerability in Web Server Function on MELSEC Series

Noroxi assessment

Priority: Monitor (action score 36/100)

  • 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: 1.1% (FIRST EPSS); higher than 67.6% 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.
  • Severity is disputed: the assigning authority (CNA) scores it 5.9, NVD 9.1.

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

Predictable Seed in Pseudo-Random Number Generator (PRNG) vulnerability in Mitsubishi Electric Corporation MELSEC iQ-F Series FX5U-xMy/z (x=32,64,80, y=T,R, z=ES,DS,ESS,DSS) with serial number 17X**** or later, and versions 1.280 and prior, Mitsubishi Electric Corporation MELSEC iQ-F Series FX5U-xMy/z (x=32,64,80, y=T,R, z=ES,DS,ESS,DSS) with serial number 179**** and prior, and versions 1.074 and prior, Mitsubishi Electric Corporation MELSEC iQ-F Series FX5UC-xMy/z (x=32,64,96, y=T, z=D,DSS)) with serial number 17X**** or later, and versions 1.280 and prior, Mitsubishi Electric Corporation MELSEC iQ-F Series FX5UC-xMy/z (x=32,64,96, y=T, z=D,DSS)) with serial number 179**** and prior, and versions 1.074 and prior, Mitsubishi Electric Corporation MELSEC iQ-F Series FX5UC-32MT/DS-TS versions 1.280 and prior, Mitsubishi Electric Corporation MELSEC iQ-F Series FX5UC-32MT/DSS-TS versions 1.280 and prior, Mitsubishi Electric Corporation MELSEC iQ-F Series FX5UJ-xMy/z (x=24,40,60, y=T,R, z=ES,ESS) versions 1.042 and prior, Mitsubishi Electric Corporation MELSEC iQ-F Series FX5UJ-xMy/ES-A (x=24,40,60, y=T,R) versions 1.043 and prior, Mitsubishi Electric Corporation MELSEC iQ-F Series FX5S-xMy/z (x=30,40,60,80, y=T,R, z=ES,ESS) versions 1.003 and prior, Mitsubishi Electric Corporation MELSEC iQ-F Series FX5UC-32MR/DS-TS versions 1.280 and prior, Mitsubishi Electric Corporation MELSEC iQ-R Series R00/01/02CPU versions 33 and prior, Mitsubishi Electric Corporation MELSEC iQ-R Series R04/08/16/32/120(EN)CPU versions 66 and prior allows a remote unauthenticated attacker to access the Web server function by guessing the random numbers used for authentication from several used random numbers.

CriticalCVSS 9.1 · v3.1—No exploit No fix recorded
Published
Jan 20, 2023
Updated
Jun 17, 2026
EPSS
1.1% · 67th percentile

Report tools

JSON

Action score

36

Monitor

Low priority for now.

CVSS
36 / 40 · 9.1 / 10
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 1.1%

CISA SSVC decision

Exploitation
proof of concept
Automatable
no
Technical impact
partial

Vulnrichment: CISA's decision-tree inputs.

CNA vs NVD score

NVD
9.1
CNA · Mitsubishi
5.9
3.2 point gap

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

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.

Follow CVE-2022-40267

When you'll hear from us

  • when it enters CISA KEV
  • when exploit code appears or is weaponized
  • when the record is updated (including a fixed version)
  • when EPSS rises 20 points in a week

One daily email digest (06:00 UTC); connect a webhook for KEV listings and weaponized exploits instantly.

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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.

VendorProduct
mitsubishielectricfx5u-80mt\/ess firmware
mitsubishielectricfx5u-80mt\/ess
mitsubishielectricfx5u-32mt\/dss firmware
mitsubishielectricfx5u-32mt\/dss
mitsubishielectricfx5u-64mt\/dss firmware
mitsubishielectricfx5u-64mt\/dss
mitsubishielectricfx5u-80mt\/dss firmware
mitsubishielectricfx5u-80mt\/dss
mitsubishielectricfx5uc-32mt\/d firmware
mitsubishielectricfx5uc-32mt\/d
mitsubishielectricfx5uc-64mt\/d firmware
mitsubishielectricfx5uc-64mt\/d

and 94 more

Affected versions

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

  • mitsubishielectric fx5s-30mr/es firmwarebefore 1.003
  • mitsubishielectric fx5s-30mt/es firmwarebefore 1.003
  • mitsubishielectric fx5s-30mt/ess firmwarebefore 1.003
  • mitsubishielectric fx5s-40mr/es firmwarebefore 1.003
  • mitsubishielectric fx5s-40mt/es firmwarebefore 1.003
  • mitsubishielectric fx5s-40mt/ess firmwarebefore 1.003
  • mitsubishielectric fx5s-60mr/es firmwarebefore 1.003
  • mitsubishielectric fx5s-60mt/es firmwarebefore 1.003
  • mitsubishielectric fx5s-60mt/ess firmwarebefore 1.003
  • mitsubishielectric fx5s-80mr/es firmwarebefore 1.003
  • mitsubishielectric fx5s-80mt/es firmwarebefore 1.003
  • mitsubishielectric fx5s-80mt/ess firmwarebefore 1.003
  • mitsubishielectric fx5u-32mt/dss firmwareall versions
  • mitsubishielectric fx5u-64mt/dss firmwareall versions
  • mitsubishielectric fx5u-80mt/dss firmwareall versions
  • mitsubishielectric fx5u-80mt/ess firmwareall versions
  • mitsubishielectric fx5uc-32mr/ds-ts firmwarebefore 1.280
  • mitsubishielectric fx5uc-32mt/d firmwareall versions
  • mitsubishielectric fx5uc-32mt/ds-ts firmwarebefore 1.280
  • mitsubishielectric fx5uc-32mt/dss 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 MELSEC iQ-F Seres FX5U-80MT/ES

    • serial number 17X**** or later, and versions 1.280 and prior, serial number 179**** and prior, and versions 1.074 and prioraffected

  • Mitsubishi Electric Corporation MELSEC iQ-F Series FX5S-30MR/ES

    • 1.003 and prioraffected

  • Mitsubishi Electric Corporation MELSEC iQ-F Series FX5S-30MT/ES

    • 1.003 and prioraffected

  • Mitsubishi Electric Corporation MELSEC iQ-F Series FX5S-30MT/ESS

    • 1.003 and prioraffected

  • Mitsubishi Electric Corporation MELSEC iQ-F Series FX5S-40MR/ES

    • 1.003 and prioraffected

  • Mitsubishi Electric Corporation MELSEC iQ-F Series FX5S-40MT/ES

    • 1.003 and prioraffected

  • Mitsubishi Electric Corporation MELSEC iQ-F Series FX5S-40MT/ESS

    • 1.003 and prioraffected

  • Mitsubishi Electric Corporation MELSEC iQ-F Series FX5S-60MR/ES

    • 1.003 and prioraffected

  • Mitsubishi Electric Corporation MELSEC iQ-F Series FX5S-60MT/ES

    • 1.003 and prioraffected

  • Mitsubishi Electric Corporation MELSEC iQ-F Series FX5S-60MT/ESS

    • 1.003 and prioraffected

  • Mitsubishi Electric Corporation MELSEC iQ-F Series FX5S-80MR/ES

    • 1.003 and prioraffected

  • Mitsubishi Electric Corporation MELSEC iQ-F Series FX5S-80MT/ES

    • 1.003 and prioraffected

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).

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
high · data can be read
Integrity
high · data or configuration can be modified
Availability
none
Attack vector
Network
Attack complexity
Low
Privileges required
None
User interaction
None
Scope
Unchanged
Confidentiality impact
High
Integrity impact
High
Availability impact
None

Weakness class (CWE)

CWE-337 · Predictable Seed in Pseudo-Random Number Generator (PRNG)

CVSS vector

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

nvd-primary

Attack context

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

MITRE has no CAPEC/ATT&CK mapping for this CWE.

Change log

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

References

Show all references (3 more)

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

All records