VulnerabilityPublished 19 Nov 2024Updated 31 Mar 2026

CVE-2024-8403: Mitsubishi Electric MELSEC iQ-F Series FX5-ENET · Improper Validation of Specified Type of Input

Affects Mitsubishi Electric MELSEC iQ-F Series FX5-ENETSource CVE Database V5

Not known to be exploited · CVSS 7.5 High.

Data as of 26 Oct 2026, 10:12 UTC

CVSS 3.1 base score

7.5High

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

EPSS: 0.6% chance of exploitation in 30 days – higher than 52% 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:H

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

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: High: There is total loss of availability, resulting in the attacker being able to fully deny access to resources in the impacted component; this loss is either sustained (while the attacker continues to deliver the attack) or persistent (the condition persists even after the attack has completed). Alternatively, the attacker has the ability to deny some availability, but the loss of availability presents a direct, serious consequence to the impacted component (e.g., the attacker cannot disrupt existing connections, but can prevent new connections; the attacker can repeatedly exploit a vulnerability that, in each instance of a successful attack, leaks a only small amount of memory, but after repeated exploitation causes a service to become completely unavailable).

Definitions: FIRST CVSS v3.1 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 19 Nov 2024
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 26 Oct 2026.

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 or the CVSS exploit maturity 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 FX5-ENET	Affected >=1.100 <=1.200	Fixed in–

AI-suggested

Monitor Mitsubishi Electric communications for official patches or firmware updates addressing CVE-2024-8403 and apply them promptly once available.
Implement strict network segmentation to isolate industrial control systems and PLCs from general IT networks and the internet, reducing exposure to remote attacks.
Deploy network-level filtering to block or restrict unauthorized SLMP protocol traffic, especially from untrusted sources.
Use intrusion detection/prevention systems (IDS/IPS) tuned to detect anomalous or malformed SLMP packets that could indicate exploitation attempts.
Conduct regular security audits and vulnerability assessments of industrial control networks to identify and remediate exposure points.
Establish incident response plans specific to industrial control system disruptions to minimize downtime and ensure rapid recovery.
Limit access to PLC management interfaces to trusted personnel and secure communication channels with encryption and authentication where possible.
Maintain up-to-date asset inventories to quickly identify affected devices and prioritize remediation efforts.

Description

Improper Validation of Specified Type of Input vulnerability in Mitsubishi Electric Corporation MELSEC iQ-F Series FX5-ENET versions 1.100 to 1.200 and FX5-ENET/IP versions 1.100 to 1.104 allows a remote attacker to cause a Denial of Service condition in Ethernet communication of the products by sending specially crafted SLMP packets.

Impact

The primary impact of CVE-2024-8403 is a denial of service condition affecting Ethernet communication of Mitsubishi MELSEC iQ-F Series FX5-ENET modules. This can lead to loss of connectivity between programmable logic controllers (PLCs) and supervisory control and data acquisition (SCADA) systems or other networked industrial devices. Such disruptions can halt or degrade industrial processes, causing production downtime, safety risks, and financial losses. Since these PLCs are often integral to critical infrastructure and manufacturing environments, the availability impact can cascade into broader operational failures. Although confidentiality and integrity are not directly compromised, the loss of availability in industrial control systems can indirectly affect safety and reliability. The ease of remote exploitation without authentication increases the threat level, especially in environments where these devices are exposed to untrusted networks or insufficiently segmented industrial networks. Organizations relying on these Mitsubishi PLCs in sectors like manufacturing, energy, transportation, and utilities could face significant operational risks if this vulnerability is exploited.

CWE-1287Improper Validation of Specified Type of Input (opens in a new tab)
Base weakness
The product receives input that is expected to be of a certain type, but it does not validate or incorrectly validates that the input is actually of the expected type.
Implementation · Input Validation
Assume all input is malicious. Use an "accept known good" input validation strategy, i.e., use a list of acceptable inputs that strictly conform to specifications. Reject any input that does not strictly conform to specifications, or transform it into something that does.
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)
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 31 Mar 2026, 04:53 UTC

WeaknessesCWE-1287

Technical details

References

Community reviews

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