CVE-2023-3373Network attack vector

FTP session hijacking via predictable data ports

Published Aug 3, 2023 · Updated Feb 27, 2025

Predictable FTP ports in Mitsubishi Electric GT21 and GS21 01.49.000 and earlier allow remote attackers to hijack data connections. The FTP server chooses passive-mode data-connection listening ports predictably, so an unauthenticated peer can guess the port and connect before the intended client. The FTP server function must be enabled and a legitimate transfer must create the listener; winning the race permits session hijacking or blocks the intended connection.

CVSS severity5.9
Medium
EPSS probability1.02%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Predictable FTP ports in Mitsubishi Electric GT21 and GS21 01.49.000 and earlier allow remote attackers to hijack data connections. The FTP server chooses passive-mode data-connection listening ports predictably, so an unauthenticated peer can guess the port and connect before the intended client. The FTP server function must be enabled and a legitimate transfer must create the listener; winning the race permits session hijacking or blocks the intended connection.

The record

CVE
CVE-2023-3373
Published
Aug 3, 2023
Updated
Feb 27, 2025
Vendor
Mitsubishi Electric Corporation
Product
GOT2000 Series GT21 model
Classifications
CWE-342, T0814
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Aug 3, 2023CVE publishedPublication date reported by the CVE source.
  2. Feb 27, 2025Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=01.49.000 and prior

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Mitsubishi Electric Corporation · GOT2000 Series GT21 modelversion=01.49.000 and prior
Mitsubishi Electric Corporation · GOT SIMPLE Series GS21 modelversion=01.49.000 and prior

Published CVSS scores

5.9Mitsubishi Electric CorporationCVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:N/I:H/A:L
9.1NIST National Vulnerability DatabaseCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-342Predictable Exact Value from Previous Values
T0814Denial of Service

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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