CVE-2025-10259VulnerabilityPublished 6 Nov 2025Updated 14 Nov 2025

CVE-2025-10259: Mitsubishi Electric MELSEC iQ-F Series FX5U-32MT/ES · Improper Validation of Specified Quantity in Input

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 26 Oct 2026, 07:57 UTC

CVSS 3.1 base score

5.3Medium

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

EPSS: 0.4% chance of exploitation in 30 days – higher than 38% 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 6 Nov 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 2026-10-26.

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 *	Fixed in–

AI-suggested

1. Implement strict network segmentation to isolate MELSEC iQ-F Series PLCs from general IT networks and the internet, limiting exposure to untrusted sources. 2. Configure firewalls and intrusion prevention systems to restrict TCP traffic to only trusted management and control stations, blocking unsolicited or malformed packets. 3. Monitor network traffic for anomalies or repeated connection resets targeting PLC IP addresses, enabling early detection of exploitation attempts. 4. Apply vendor-provided patches or firmware updates promptly once available to address the root cause of the vulnerability. 5. Employ secure communication protocols or VPNs for remote access to PLCs to reduce exposure to crafted TCP packets. 6. Conduct regular security assessments and penetration testing focused on industrial control systems to identify and remediate similar vulnerabilities. 7. Maintain an inventory of all Mitsubishi Electric PLCs deployed and ensure they are included in vulnerability management programs. 8. Train operational technology (OT) personnel on recognizing and responding to network-based DoS attacks targeting control devices.

Description

Improper Validation of Specified Quantity in Input vulnerability in TCP Communication Function on Mitsubishi Electric Corporation MELSEC iQ-F Series CPU module allows a remote attacker to disconnect the connection by sending specially crafted TCP packets to cause a denial-of-service (DoS) condition on the products. There is no impact on connections other than the attacked one.

Impact

For European organizations, particularly those in industrial automation, manufacturing, and critical infrastructure sectors, this vulnerability poses a risk of targeted denial-of-service attacks on Mitsubishi Electric MELSEC iQ-F Series PLCs. Disruption of TCP connections could lead to temporary loss of communication between control systems and field devices, potentially causing operational delays, production downtime, or safety system interruptions. Although the impact is limited to availability and does not compromise data confidentiality or integrity, even short-term outages in industrial control systems can have significant financial and safety consequences. The vulnerability's ease of exploitation without authentication increases the risk from internal or external threat actors with network access. European organizations with network-exposed PLCs or insufficient network segmentation are particularly vulnerable. The lack of known exploits in the wild reduces immediate risk but does not eliminate the threat, especially as attackers may develop exploits over time.

CWE-1284Improper Validation of Specified Quantity in Input (opens in a new tab)
Base weakness
The product receives input that is expected to specify a quantity (such as size or length), but it does not validate or incorrectly validates that the quantity has the required properties.
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

Loading reviews…

Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 20 Nov 2025, 08:33 UTC

WeaknessesCWE-1284

Technical details

References

Community reviews

Related threats