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

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.

Published: 2023-01-20 Last update: 2026-06-17 Assigner: [email protected] Source: [email protected]
NVD Status：Modified，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2022-40267 is rated Moderate Risk (44.9/100): CVSS Medium severity, with medium exploitation likelihood (EPSS 1.18%). Review affected assets and schedule remediation.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Exploit prediction scoring system (EPSS) score for CVE-2022-40267

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-06-15 2.18% 1.18% -1.00%
2 2026-02-22 2.26% 2.18% -0.08%
3 2026-02-02 — 2.26% —

Full EPSS history (25 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2022-40267

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
5.9 3.1 MEDIUM
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:N Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:H)
Even with access, the exploit needs extra luck, timing, or a fussy environment to actually work.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:N)
Doesn’t really leak secrets in a meaningful way.
Integrity (I:H)
They could widely tamper with or forge data—trust in the data is badly hurt.
Availability (A:N)
Service keeps running; no real outage angle.
 2.2 3.6 [email protected]
9.1 3.1 CRITICAL
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:H)
Serious risk that confidential data gets exposed in a big way.
Integrity (I:H)
They could widely tamper with or forge data—trust in the data is badly hurt.
Availability (A:N)
Service keeps running; no real outage angle.
 3.9 5.2 [email protected]

Weakness enumeration for CVE-2022-40267

Affected software / configurations for CVE-2022-40267

Vendor Product Version Raw CPE
mitsubishielectric fx5u-80mt\/ess_firmware — cpe:2.3:o:mitsubishielectric:fx5u-80mt\/ess_firmware:-:*:*:*:*:*:*:*
mitsubishielectric fx5u-32mt\/dss_firmware — cpe:2.3:o:mitsubishielectric:fx5u-32mt\/dss_firmware:-:*:*:*:*:*:*:*
mitsubishielectric fx5u-64mt\/dss_firmware — cpe:2.3:o:mitsubishielectric:fx5u-64mt\/dss_firmware:-:*:*:*:*:*:*:*
mitsubishielectric fx5u-80mt\/dss_firmware — cpe:2.3:o:mitsubishielectric:fx5u-80mt\/dss_firmware:-:*:*:*:*:*:*:*
mitsubishielectric fx5uc-32mt\/d_firmware — cpe:2.3:o:mitsubishielectric:fx5uc-32mt\/d_firmware:-:*:*:*:*:*:*:*
mitsubishielectric fx5uc-64mt\/d_firmware — cpe:2.3:o:mitsubishielectric:fx5uc-64mt\/d_firmware:-:*:*:*:*:*:*:*
mitsubishielectric fx5uc-96mt\/d_firmware — cpe:2.3:o:mitsubishielectric:fx5uc-96mt\/d_firmware:-:*:*:*:*:*:*:*
mitsubishielectric fx5uc-32mt\/dss_firmware — cpe:2.3:o:mitsubishielectric:fx5uc-32mt\/dss_firmware:-:*:*:*:*:*:*:*
mitsubishielectric fx5uc-64mt\/dss_firmware — cpe:2.3:o:mitsubishielectric:fx5uc-64mt\/dss_firmware:-:*:*:*:*:*:*:*
mitsubishielectric fx5uc-96mt\/dss_firmware — cpe:2.3:o:mitsubishielectric:fx5uc-96mt\/dss_firmware:-:*:*:*:*:*:*:*
mitsubishielectric fx5uc-32mt\/ds-ts_firmware < 1.280 cpe:2.3:o:mitsubishielectric:fx5uc-32mt\/ds-ts_firmware:*:*:*:*:*:*:*:*
mitsubishielectric fx5uc-32mt\/dss-ts_firmware < 1.280 cpe:2.3:o:mitsubishielectric:fx5uc-32mt\/dss-ts_firmware:*:*:*:*:*:*:*:*
mitsubishielectric fx5uc-32mr\/ds-ts_firmware < 1.280 cpe:2.3:o:mitsubishielectric:fx5uc-32mr\/ds-ts_firmware:*:*:*:*:*:*:*:*
mitsubishielectric r00cpu_firmware — cpe:2.3:o:mitsubishielectric:r00cpu_firmware:-:*:*:*:*:*:*:*
mitsubishielectric r01cpu_firmware — cpe:2.3:o:mitsubishielectric:r01cpu_firmware:-:*:*:*:*:*:*:*
mitsubishielectric r02cpu_firmware — cpe:2.3:o:mitsubishielectric:r02cpu_firmware:-:*:*:*:*:*:*:*
mitsubishielectric r04cpu_firmware — cpe:2.3:o:mitsubishielectric:r04cpu_firmware:-:*:*:*:*:*:*:*
mitsubishielectric r08cpu_firmware — cpe:2.3:o:mitsubishielectric:r08cpu_firmware:-:*:*:*:*:*:*:*
mitsubishielectric r16cpu_firmware — cpe:2.3:o:mitsubishielectric:r16cpu_firmware:-:*:*:*:*:*:*:*
mitsubishielectric r32cpu_firmware — cpe:2.3:o:mitsubishielectric:r32cpu_firmware:-:*:*:*:*:*:*:*
mitsubishielectric r120cpu_firmware — cpe:2.3:o:mitsubishielectric:r120cpu_firmware:-:*:*:*:*:*:*:*
mitsubishielectric r04encpu_firmware — cpe:2.3:o:mitsubishielectric:r04encpu_firmware:-:*:*:*:*:*:*:*
mitsubishielectric r08encpu_firmware — cpe:2.3:o:mitsubishielectric:r08encpu_firmware:-:*:*:*:*:*:*:*
mitsubishielectric r16encpu_firmware — cpe:2.3:o:mitsubishielectric:r16encpu_firmware:-:*:*:*:*:*:*:*
mitsubishielectric r32encpu_firmware — cpe:2.3:o:mitsubishielectric:r32encpu_firmware:-:*:*:*:*:*:*:*
mitsubishielectric r120encpu_firmware — cpe:2.3:o:mitsubishielectric:r120encpu_firmware:-:*:*:*:*:*:*:*
mitsubishielectric fx5uj-24mt\/es_firmware < 1.042 cpe:2.3:o:mitsubishielectric:fx5uj-24mt\/es_firmware:*:*:*:*:*:*:*:*
mitsubishielectric fx5uj-40mt\/es_firmware < 1.042 cpe:2.3:o:mitsubishielectric:fx5uj-40mt\/es_firmware:*:*:*:*:*:*:*:*
mitsubishielectric fx5uj-60mt\/es_firmware < 1.042 cpe:2.3:o:mitsubishielectric:fx5uj-60mt\/es_firmware:*:*:*:*:*:*:*:*
mitsubishielectric fx5uj-24mr\/es_firmware < 1.042 cpe:2.3:o:mitsubishielectric:fx5uj-24mr\/es_firmware:*:*:*:*:*:*:*:*
mitsubishielectric fx5uj-40mr\/es_firmware < 1.042 cpe:2.3:o:mitsubishielectric:fx5uj-40mr\/es_firmware:*:*:*:*:*:*:*:*
mitsubishielectric fx5uj-60mr\/es_firmware < 1.042 cpe:2.3:o:mitsubishielectric:fx5uj-60mr\/es_firmware:*:*:*:*:*:*:*:*
mitsubishielectric fx5uj-24mt\/ess_firmware < 1.042 cpe:2.3:o:mitsubishielectric:fx5uj-24mt\/ess_firmware:*:*:*:*:*:*:*:*
mitsubishielectric fx5uj-40mt\/ess_firmware < 1.042 cpe:2.3:o:mitsubishielectric:fx5uj-40mt\/ess_firmware:*:*:*:*:*:*:*:*
mitsubishielectric fx5uj-60mt\/ess_firmware < 1.042 cpe:2.3:o:mitsubishielectric:fx5uj-60mt\/ess_firmware:*:*:*:*:*:*:*:*
mitsubishielectric fx5uj-24mt\/es-a_firmware < 1.043 cpe:2.3:o:mitsubishielectric:fx5uj-24mt\/es-a_firmware:*:*:*:*:*:*:*:*
mitsubishielectric fx5uj-40mt\/es-a_firmware < 1.043 cpe:2.3:o:mitsubishielectric:fx5uj-40mt\/es-a_firmware:*:*:*:*:*:*:*:*
mitsubishielectric fx5uj-60mt\/es-a_firmware < 1.043 cpe:2.3:o:mitsubishielectric:fx5uj-60mt\/es-a_firmware:*:*:*:*:*:*:*:*
mitsubishielectric fx5uj-24mr\/es-a_firmware < 1.043 cpe:2.3:o:mitsubishielectric:fx5uj-24mr\/es-a_firmware:*:*:*:*:*:*:*:*
mitsubishielectric fx5uj-40mr\/es-a_firmware < 1.043 cpe:2.3:o:mitsubishielectric:fx5uj-40mr\/es-a_firmware:*:*:*:*:*:*:*:*
mitsubishielectric fx5uj-60mr\/es-a_firmware < 1.043 cpe:2.3:o:mitsubishielectric:fx5uj-60mr\/es-a_firmware:*:*:*:*:*:*:*:*
mitsubishielectric fx5s-30mt\/es_firmware < 1.003 cpe:2.3:o:mitsubishielectric:fx5s-30mt\/es_firmware:*:*:*:*:*:*:*:*
mitsubishielectric fx5s-40mt\/es_firmware < 1.003 cpe:2.3:o:mitsubishielectric:fx5s-40mt\/es_firmware:*:*:*:*:*:*:*:*
mitsubishielectric fx5s-60mt\/es_firmware < 1.003 cpe:2.3:o:mitsubishielectric:fx5s-60mt\/es_firmware:*:*:*:*:*:*:*:*
mitsubishielectric fx5s-80mt\/es_firmware < 1.003 cpe:2.3:o:mitsubishielectric:fx5s-80mt\/es_firmware:*:*:*:*:*:*:*:*
mitsubishielectric fx5s-30mr\/es_firmware < 1.003 cpe:2.3:o:mitsubishielectric:fx5s-30mr\/es_firmware:*:*:*:*:*:*:*:*
mitsubishielectric fx5s-40mr\/es_firmware < 1.003 cpe:2.3:o:mitsubishielectric:fx5s-40mr\/es_firmware:*:*:*:*:*:*:*:*
mitsubishielectric fx5s-60mr\/es_firmware < 1.003 cpe:2.3:o:mitsubishielectric:fx5s-60mr\/es_firmware:*:*:*:*:*:*:*:*
mitsubishielectric fx5s-80mr\/es_firmware < 1.003 cpe:2.3:o:mitsubishielectric:fx5s-80mr\/es_firmware:*:*:*:*:*:*:*:*
mitsubishielectric fx5s-30mt\/ess_firmware < 1.003 cpe:2.3:o:mitsubishielectric:fx5s-30mt\/ess_firmware:*:*:*:*:*:*:*:*
mitsubishielectric fx5s-40mt\/ess_firmware < 1.003 cpe:2.3:o:mitsubishielectric:fx5s-40mt\/ess_firmware:*:*:*:*:*:*:*:*
mitsubishielectric fx5s-60mt\/ess_firmware < 1.003 cpe:2.3:o:mitsubishielectric:fx5s-60mt\/ess_firmware:*:*:*:*:*:*:*:*
mitsubishielectric fx5s-80mt\/ess_firmware < 1.003 cpe:2.3:o:mitsubishielectric:fx5s-80mt\/ess_firmware:*:*:*:*:*:*:*:*

References for CVE-2022-40267

cvelogic Threat Intelligence