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Fencer Vulns
medium 5.9

CVE-2022-40267 json

Authentication Bypass Vulnerability in Web Server Function on MELSEC Series

published 2023-01-20 3 y ago modified 2026-06-17 4 mo ago also EUVD-2022-43565

cvss
5.9
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
1.2%
EPSS 1.2% chance of exploitation in 30 days, percentile 69%
public exploits
0
none known

Summary

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.

Patch / fix

  • mitsubishielectric fx5uc-32mt/ds-ts_firmware 1.280
  • mitsubishielectric fx5uc-32mt/dss-ts_firmware 1.280
  • mitsubishielectric fx5uc-32mr/ds-ts_firmware 1.280
  • mitsubishielectric fx5uj-24mt/es_firmware 1.042
  • mitsubishielectric fx5uj-40mt/es_firmware 1.042
  • mitsubishielectric fx5uj-60mt/es_firmware 1.042
  • mitsubishielectric fx5uj-24mr/es_firmware 1.042
  • mitsubishielectric fx5uj-40mr/es_firmware 1.042
  • mitsubishielectric fx5uj-60mr/es_firmware 1.042
  • mitsubishielectric fx5uj-24mt/ess_firmware 1.042
  • mitsubishielectric fx5uj-40mt/ess_firmware 1.042
  • mitsubishielectric fx5uj-60mt/ess_firmware 1.042
  • mitsubishielectric fx5uj-24mt/es-a_firmware 1.043
  • mitsubishielectric fx5uj-40mt/es-a_firmware 1.043
  • mitsubishielectric fx5uj-60mt/es-a_firmware 1.043
  • mitsubishielectric fx5uj-24mr/es-a_firmware 1.043
  • mitsubishielectric fx5uj-40mr/es-a_firmware 1.043
  • mitsubishielectric fx5uj-60mr/es-a_firmware 1.043
  • mitsubishielectric fx5s-30mt/es_firmware 1.003
  • mitsubishielectric fx5s-40mt/es_firmware 1.003

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

cisa ICSA-23-017-02 updated cvss 5.9

Mitsubishi Electric MELSEC iQ-F, iQ-R Series

  • Mitsubishi Electric FX5S-xMy/z* x=30,40,60,80, y=T,R, z=ES,ESS <= 1.003 Mitsubishi Electric FX5U-xMy/z x=32,64,80, y=T,R, z=ES,DS,ESS,DSS <= 1.280, <= 1.074 Mitsubishi Electric FX5UC-xMy/z x=32,64,96 y=T, z=D,DSS <= 1.280, <= 1.074 Mitsubishi Electric FX5UJ-xMy/ES-A* x=24,40,60, y=T,R <= 1.043 Mitsubishi Electric FX5UJ-xMy/z x=24,40,60, y=T,R, z=ES,ESS <= 1.042 Mitsubishi Electric MELSEC iQ-F Series FX5UC-32MT/DS-TS, FX5UC-32MT/DSS-TS, FX5UC-32MR/DS-TS <= 1.280
    +2 more products
    Mitsubishi Electric MELSEC iQ-R Series R00/01/02CPU <= 33 Mitsubishi Electric MELSEC iQ-R Series R04/08/16/32/120(EN)CPU <= 66
    affected: mitigation “MELSEC iQ-F Series with serial number 17X**** or later: FX5U-xMy/z x=32,64,80, y=T,R, z=ES,DS,ESS,DSS: Update to v1.281 or later FX5UC-xMy/z x=32,64,96 y=T, z=D,DSS: Update to v1.281 or later” mitsubishielectric.com

From CISA ICS and IT advisories (CSAF, https://github.com/cisagov/CSAF), a U.S. Government work; changed: reduced to products, statuses and remediations. CISA notification · csaf

CISA SSVC

Exploitation
Proof of concept is public
Automatable
no
Technical impact
partial
Assessed
2 y ago

Exploit prediction

1.24% chance of exploitation in the next 30 days, higher than 69% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CNA 3.1 5.9 CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:N
NVD 3.1 9.1 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N

Affected products

  • Mitsubishi Electric Corporation MELSEC iQ-F Series FX5U-32MT/ES
  • Mitsubishi Electric Corporation MELSEC iQ-F Series FX5U-64MT/ES
  • Mitsubishi Electric Corporation MELSEC iQ-F Seres FX5U-80MT/ES
  • Mitsubishi Electric Corporation MELSEC iQ-F Series FX5U-32MR/ES
  • Mitsubishi Electric Corporation MELSEC iQ-F Series FX5U-64MR/ES
  • Mitsubishi Electric Corporation MELSEC iQ-F Series FX5U-80MR/ES
  • Mitsubishi Electric Corporation MELSEC iQ-F Series FX5U-32MT/DS
  • Mitsubishi Electric Corporation MELSEC iQ-F Series FX5U-64MT/DS
  • Mitsubishi Electric Corporation MELSEC iQ-F Series FX5U-80MT/DS
  • Mitsubishi Electric Corporation MELSEC iQ-F Series FX5U-32MR/DS
  • Mitsubishi Electric Corporation MELSEC iQ-F Series FX5U-64MR/DS
  • Mitsubishi Electric Corporation MELSEC iQ-F Series FX5U-80MR/DS
  • Mitsubishi Electric Corporation MELSEC iQ-F Series FX5U-32MT/ESS
  • Mitsubishi Electric Corporation MELSEC iQ-F Series FX5U-64MT/ESS
  • Mitsubishi Electric Corporation MELSEC iQ-F Series FX5U-80MT/ESS
  • Mitsubishi Electric Corporation MELSEC iQ-F Series FX5U-32MT/DSS
  • Mitsubishi Electric Corporation MELSEC iQ-F Series FX5U-64MT/DSS
  • Mitsubishi Electric Corporation MELSEC iQ-F Series FX5U-80MT/DSS
  • Mitsubishi Electric Corporation MELSEC iQ-F Series FX5UC-32MT/D
  • Mitsubishi Electric Corporation MELSEC iQ-F Series FX5UC-64MT/D
  • Mitsubishi Electric Corporation MELSEC iQ-F Series FX5UC-96MT/D
  • Mitsubishi Electric Corporation MELSEC iQ-F Series FX5UC-32MT/DSS
  • Mitsubishi Electric Corporation MELSEC iQ-F Series FX5UC-64MT/DSS
  • Mitsubishi Electric Corporation MELSEC iQ-F Series FX5UC-96MT/DSS
  • Mitsubishi Electric Corporation MELSEC iQ-F Series FX5UC-32MT/DS-TS
  • Mitsubishi Electric Corporation MELSEC iQ-F Series FX5UC-32MT/DSS-TS
  • Mitsubishi Electric Corporation MELSEC iQ-F Series FX5UC-32MR/DS-TS
  • Mitsubishi Electric Corporation MELSEC iQ-R Series R00CPU
  • Mitsubishi Electric Corporation MELSEC iQ-R Series R01CPU
  • Mitsubishi Electric Corporation MELSEC iQ-R Series R02CPU
  • Mitsubishi Electric Corporation MELSEC iQ-R Series R04CPU
  • Mitsubishi Electric Corporation MELSEC iQ-R Series R08CPU
  • Mitsubishi Electric Corporation MELSEC iQ-R Series R16CPU
  • Mitsubishi Electric Corporation MELSEC iQ-R Series R32CPU
  • Mitsubishi Electric Corporation MELSEC iQ-R Series R120CPU
  • Mitsubishi Electric Corporation MELSEC iQ-R Series R04ENCPU
  • Mitsubishi Electric Corporation MELSEC iQ-R Series R08ENCPU
  • Mitsubishi Electric Corporation MELSEC iQ-R Series R16ENCPU
  • Mitsubishi Electric Corporation MELSEC iQ-R Series R32ENCPU
  • Mitsubishi Electric Corporation MELSEC iQ-R Series R120ENCPU
  • Mitsubishi Electric Corporation MELSEC iQ-F Series FX5UJ-24MT/ES
  • Mitsubishi Electric Corporation MELSEC iQ-F Series FX5UJ-40MT/ES
  • Mitsubishi Electric Corporation MELSEC iQ-F Series FX5UJ-60MT/ES
  • Mitsubishi Electric Corporation MELSEC iQ-F Series FX5UJ-24MR/ES
  • Mitsubishi Electric Corporation MELSEC iQ-F Series FX5UJ-40MR/ES
  • Mitsubishi Electric Corporation MELSEC iQ-F Series FX5UJ-60MR/ES
  • Mitsubishi Electric Corporation MELSEC iQ-F Series FX5UJ-24MT/ESS
  • Mitsubishi Electric Corporation MELSEC iQ-F Series FX5UJ-40MT/ESS
  • Mitsubishi Electric Corporation MELSEC iQ-F Series FX5UJ-60MT/ESS
  • Mitsubishi Electric Corporation MELSEC iQ-F Series FX5UJ-24MT/ES-A

Classification

Weakness
  • CWE-337 Predictable Seed in Pseudo-Random Number Generator (PRNG)
  • CWE-335 Incorrect Usage of Seeds in Pseudo-Random Number Generator (PRNG)

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.