CVE-2023-6374VulnerabilityPublished 30 Jan 2024Updated 9 Jun 2025

CVE-2023-6374: Mitsubishi Electric MELSEC WS Series WS0-GETH00200 · Authentication Bypass by Capture-replay

Affects Mitsubishi Electric MELSEC WS Series WS0-GETH00200Source CVE Database V5

Not known to be exploited · CVSS 5.9 Medium.

Data as of 26 Oct 2026, 06:26 UTC

CVSS 3.1 base score

5.9Medium

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

EPSS: 0.7% chance of exploitation in 30 days – higher than 54% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.

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

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

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: High: A successful attack depends on conditions beyond the attacker's control. That is, a successful attack cannot be accomplished at will, but requires the attacker to invest in some measurable amount of effort in preparation or execution against the vulnerable component before a successful attack can be expected. For example, a successful attack may require an attacker to: gather knowledge about the environment in which the vulnerable target/component exists; prepare the target environment to improve exploit reliability; or inject themselves into the logical network path between the target and the resource requested by the victim in order to read and/or modify network communications (e.g., a man in the middle attack).
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: High: There is a total loss of integrity, or a complete loss of protection. For example, the attacker is able to modify any/all files protected by the impacted component. Alternatively, only some files can be modified, but malicious modification would present a direct, serious consequence to the impacted component.
Availability: None: There is no impact to availability within the impacted component.

Definitions: FIRST CVSS v3.1 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 30 Jan 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 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

AI-suggested

1. Network Segmentation: Isolate MELSEC WS Series modules within dedicated OT network segments with strict access controls to limit exposure to untrusted networks. 2. Monitoring and Logging: Implement enhanced monitoring of network traffic to and from these modules to detect unusual authentication attempts or replay patterns. 3. Access Control: Restrict network access to the modules only to authorized management stations and use VPNs or secure tunnels for remote access. 4. Vendor Coordination: Engage with Mitsubishi Electric Corporation for official patches or firmware updates addressing this vulnerability and apply them promptly once available. 5. Replay Attack Mitigation: Where possible, deploy network-level protections such as intrusion detection/prevention systems (IDS/IPS) configured to detect replay attacks or anomalous authentication sequences. 6. Incident Response Preparedness: Develop and test incident response plans specific to OT environments to quickly isolate and remediate compromised modules. 7. Configuration Review: Audit and harden device configurations to disable unnecessary services and ensure strong authentication mechanisms are in place, if configurable. 8. Physical Security: Ensure physical access to the modules is restricted to prevent local exploitation or tampering.

Description

Authentication Bypass by Capture-replay vulnerability in Mitsubishi Electric Corporation MELSEC WS Series WS0-GETH00200 all serial numbers allows a remote unauthenticated attacker to bypass authentication by capture-replay attack and illegally login to the affected module. As a result, the remote attacker who has logged in illegally may be able to disclose or tamper with the programs and parameters in the modules.

Impact

For European organizations, especially those operating in critical infrastructure sectors such as manufacturing, energy, and utilities, this vulnerability poses a significant risk. The MELSEC WS Series modules are used in industrial automation and control systems (IACS), which are integral to operational technology (OT) environments. Unauthorized access to these modules could allow attackers to alter control logic or parameters, potentially disrupting production lines, causing equipment damage, or leading to safety incidents. While the vulnerability does not directly impact confidentiality or availability, the integrity compromise could have cascading effects on operational reliability and safety compliance. European organizations with interconnected IT and OT networks are particularly vulnerable if network segmentation is insufficient. Additionally, regulatory frameworks such as NIS2 and the EU Cybersecurity Act emphasize the protection of critical infrastructure, making exploitation of such vulnerabilities a compliance and reputational risk. The medium CVSS score suggests that exploitation requires some sophistication, but the absence of required privileges or user interaction lowers the barrier for remote attackers who can access the network segment hosting these devices.

CWE-294Authentication Bypass by Capture-replay (opens in a new tab)
Base weaknessLikelihood of exploit: HighOWASP Top 10 A07:2025: Authentication Failures (opens in a new tab)
A capture-replay flaw exists when the design of the product makes it possible for a malicious user to sniff network traffic and bypass authentication by replaying it to the server in question to the same effect as the original message (or with minor changes).
Architecture and Design
Utilize some sequence or time stamping functionality along with a checksum which takes this into account in order to ensure that messages can be parsed only once.
Architecture and Design
Since any attacker who can listen to traffic can see sequence numbers, it is necessary to sign messages with some kind of cryptography to ensure that sequence numbers are not simply doctored along with content.
OWASP Cheat Sheets
OWASP Authentication (opens in a new tab)
OWASP ASVS 4.0.3
V2.8.5 (opens in a new tab)
V2.8.4 (opens in a new tab)
V9.2.3 (opens in a new tab)
Attack patterns
Session Sidejacking (opens in a new tab)
Kerberoasting (opens in a new tab)
Remote Services with Stolen Credentials (opens in a new tab)
Windows Admin Shares with Stolen Credentials (opens in a new tab)
Reusing Session IDs (aka Session Replay) (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

Description

AI analysisMachine-generated, updated 10 Jul 2025, 22:32 UTC

WeaknessesCWE-294

Technical details

References

Community reviews

Related threats