MELSEC iQ-F Series FX5U-32MT/ES: Improper Validation of Specified Index, Position, or Offset in Input
CVE-2025-3755 is a critical-severity improper validation of specified index, position, or offset in input vulnerability in MELSEC iQ-F Series FX5U-32MT/ES from Mitsubishi Electric, with a CVSS 3.1 base score of 9.1 out of 10. It can be exploited remotely over the network by an unauthenticated attacker, without any action from a user. Affected MELSEC iQ-F Series FX5U-32MT/ES versions: All versions. The record does not name a fixed version, so check the vendor advisory. There is no confirmed exploitation so far. EPSS estimates a 0.86% chance of exploitation within 30 days, higher than 59% of scored CVEs.
Critical severity: a successful attack would have severe impact.
What to do
- Check which version of MELSEC iQ-F Series FX5U-32MT/ES you run against the affected versions below, and install the vendor's latest release.
- Read the advisory on mitsubishielectric.com for workarounds and exact fixed builds.
- Until you can update, restrict network access to the affected service so it is not reachable from untrusted networks.
Affected products and versions
Version data comes from the organisation that assigned the CVE; 35 further products are omitted here. Confirm against the vendor advisory before deciding you are unaffected.
How the severity score breaks down
- Attack vector
- NetworkCan be exploited remotely over a network, including the internet.
- Attack complexity
- LowNo special conditions are needed; the attack works reliably.
- Privileges required
- NoneNo account or login is needed.
- User interaction
- NoneNo action by a victim is required.
- Scope
- UnchangedImpact stays within the vulnerable component.
- Confidentiality
- HighAll data handled by the component can be read.
- Integrity
- NoneNothing can be modified.
- Availability
- HighThe component can be taken down completely.
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H. Scored by CNA (yd.MitsubishiElectric.co.jp).
Official description
Improper Validation of Specified Index, Position, or Offset in Input vulnerability in Mitsubishi Electric Corporation MELSEC iQ-F Series CPU modules allows a remote unauthenticated attacker to read information in the product, to cause a Denial-of-Service (DoS) condition in MELSOFT connection, or to stop the operation of the CPU module (causing a DoS condtion on the CPU module), by sending specially crafted packets. The product is needed to reset for recovery.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Improper Validation of Specified Index, Position, or Offset in Input
The product receives input that is expected to specify an index, position, or offset into an indexable resource such as a buffer or file, but it does not validate or incorrectly validates that the specified index/position/offset has the required properties.
More Improper Validation of Specified Index, Position, or Offset in Input vulnerabilities (CWE-1285)
Timeline
- CVE record published.
- CISA published its SSVC assessment (exploitation: none, automatable: yes, technical impact: total).
- Record last changed materially (score, affected products, status or references).
References
Other vulnerabilities in MELSEC iQ-F Series FX5U-32MT/ES
- 7.5 High severity
- 7.3 High severity
- 8.1 High severity
- 7.5 High severity
- 9.1 Critical severity
Recent Improper Validation of Specified Index, Position, or Offset in Input vulnerabilities
- 7.8 High severity
- 7.8 High severity
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