CVE-2025-5514VulnerabilityPublished 25 Aug 2025

CVE-2025-5514: Mitsubishi Electric MELSEC iQ-F Series FX5U-32MT/ES · Improper Handling of Length Parameter Inconsistency

Affects Mitsubishi Electric MELSEC iQ-F Series FX5U-32MT/ESSource CVE Database V5

Not known to be exploited · CVSS 5.3 Medium.

Data as of 25 Oct 2026, 19:02 UTC

CVSS 3.1 base score

5.3Medium

How severe the flaw is on the 0–10 CVSS scale.

EPSS: 0.5% chance of exploitation in 30 days – higher than 47% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.

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

Attack Vector: Network
Attack Complexity: Low
Privileges Required: None
User Interaction: None
Scope: Unchanged
Confidentiality: None
Integrity: None
Availability: Low

Bold values are the worst case: easiest to exploit or largest impact.

Attack Vector: Network: The vulnerable component is bound to the network stack and the set of possible attackers extends beyond the other options listed, up to and including the entire Internet. Such a vulnerability is often termed 'remotely exploitable' and can be thought of as an attack being exploitable at the protocol level one or more network hops away (e.g., across one or more routers).
Attack Complexity: Low: Specialized access conditions or extenuating circumstances do not exist. An attacker can expect repeatable success against the vulnerable component.
Privileges Required: None: The attacker is unauthorized prior to attack, and therefore does not require any access to settings or files to carry out an attack.
User Interaction: None: The vulnerable system can be exploited without any interaction from any user.
Scope: Unchanged: An exploited vulnerability can only affect resources managed by the same security authority. In this case, the vulnerable component and the impacted component are either the same, or both are managed by the same security authority.
Confidentiality: None: There is no loss of confidentiality within the impacted component.
Integrity: None: There is no loss of integrity within the impacted component.
Availability: Low: Performance is reduced or there are interruptions in resource availability. Even if repeated exploitation of the vulnerability is possible, the attacker does not have the ability to completely deny service to legitimate users. The resources in the impacted component are either partially available all of the time, or fully available only some of the time, but overall there is no direct, serious consequence to the impacted component.

Definitions: FIRST CVSS v3.1 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 25 Aug 2025
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 2026-10-25.

Disclosed: The CVE record is public on cve.org. Its publication is t = 0.
Detectable: A public nuclei template can find exposed instances, for defenders and attackers alike.
Weaponised: Public exploit code exists in Metasploit or Exploit-DB, or CISA SSVC reports a public proof of concept.
Exploited in the wild: CISA KEV lists it, CISA SSVC rates exploitation active, or a source reports attacks.
Observed by OffSeq Mirage: OffSeq Mirage honeypot sensors recorded attack traffic for this CVE, or found exposed hosts without attack traffic.

Moments are spaced evenly, not to scale; a dashed line marks a gap of six months or more. Deltas count from t = 0. Sources that give only a date (CISA KEV, Exploit-DB, or a time of exactly 00:00Z) read “same day” rather than hours. Metasploit modules carry the flaw’s disclosure date, not their release date, and nuclei templates carry no date, so both appear above but not on the timeline.

What to do

Affected software

Product	Affected	Fixed in
Mitsubishi Electric Corporation MELSEC iQ-F Series FX5U-32MT/ES	Affected >=1.060	Fixed in–

AI-suggested

Organizations should immediately inventory their industrial control systems to identify deployments of the MELSEC iQ-F Series FX5U-32MT/ES CPU modules running firmware version 1.060 or later. Until an official patch is released by Mitsubishi Electric, the following specific mitigations are recommended: 1) Restrict network access to the web server interface by implementing network segmentation and firewall rules to limit exposure only to trusted management networks and personnel. 2) Employ intrusion detection/prevention systems (IDS/IPS) tuned to detect anomalous HTTP requests or unusual traffic patterns targeting the PLC web server. 3) Monitor network traffic for repeated or malformed HTTP requests that could indicate exploitation attempts. 4) Disable or restrict the web server function if it is not essential for operations, or replace web-based management with alternative secure methods. 5) Coordinate with Mitsubishi Electric for firmware updates and apply patches promptly once available. 6) Conduct regular security assessments of OT networks to identify and remediate similar protocol handling vulnerabilities. These targeted mitigations go beyond generic advice by focusing on access control, traffic monitoring, and operational adjustments specific to the affected ICS components.

Description

Improper Handling of Length Parameter Inconsistency vulnerability in web server function on Mitsubishi Electric Corporation MELSEC iQ-F Series CPU module allows a remote unauthenticated attacker to delay the processing of the web server function and prevent legitimate users from utilizing the web server function, by sending a specially crafted HTTP request.

Impact

For European organizations, especially those in manufacturing, utilities, and critical infrastructure sectors that deploy Mitsubishi Electric MELSEC iQ-F Series controllers, this vulnerability poses a risk of operational disruption. The denial-of-service condition could delay or block access to web-based management interfaces, hindering monitoring, diagnostics, and control activities. This could lead to production downtime, delayed response to system faults, or impaired safety monitoring. While the vulnerability does not allow data theft or system takeover, the availability impact in industrial environments can have significant financial and safety consequences. European industries with automated manufacturing lines or infrastructure control systems using these PLCs may experience interruptions, potentially affecting supply chains and service delivery. The lack of authentication requirement and network-based exploitability increases the risk of opportunistic attacks from external threat actors or insiders with network access. However, the absence of known exploits in the wild and the medium severity rating suggest the threat is moderate but warrants timely mitigation to avoid escalation.

CWE-130Improper Handling of Length Parameter Inconsistency (opens in a new tab)
Base weakness
The product parses a formatted message or structure, but it does not handle or incorrectly handles a length field that is inconsistent with the actual length of the associated data.
Implementation
When processing structured incoming data containing a size field followed by raw data, ensure that you identify and resolve any inconsistencies between the size field and the actual size of the data.
Implementation
Do not let the user control the size of the buffer.
Implementation
Validate that the length of the user-supplied data is consistent with the buffer size.
OWASP Cheat Sheets
XML Security (opens in a new tab)
Mass Assignment (opens in a new tab)
OWASP ASVS 4.0.3
V13.3.1 (opens in a new tab)
V5.1.4 (opens in a new tab)
V5.1.3 (opens in a new tab)
Attack patterns
Buffer Overflow via Parameter Expansion (opens in a new tab)
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).

References

Community reviews

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 2 Sep 2025, 01:12 UTC

WeaknessesCWE-130

Technical details

References

Community reviews

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