CVE-2021-20613
Improper initialization vulnerability in MELSEC-F series FX3U-ENET Firmware version 1.16 and...
Improper initialization vulnerability in MELSEC-F series FX3U-ENET Firmware version 1.16 and prior, FX3U-ENET-L Firmware version 1.16 and prior and FX3U-ENET-P502 Firmware version 1.16 and prior allows a remote unauthenticated attacker to cause a denial-of-service (DoS) condition in communication function of the product by sending specially crafted packets. Control by MELSEC-F series PLC is not affected by this vulnerability, but system reset is required for recovery.
Attack profile
How easy it is to exploit
- Attack vector
- Network
- Complexity
- Low
- Privileges needed
- None
- User interaction
- None
What an attacker can affect
- Confidentiality
- None
- Integrity
- None
- Availability
- High
Exploit likelihood
What each source reports
NVD Score used
Improper initialization vulnerability in MELSEC-F series FX3U-ENET Firmware version 1.16 and prior, FX3U-ENET-L Firmware version 1.16 and prior and FX3U-ENET-P502 Firmware version 1.16 and prior allows a remote unauthenticated attacker to cause a denial-of-service (DoS) condition in communication function of the product by sending specially crafted packets. Control by MELSEC-F series PLC is not affected by this vulnerability, but system reset is required for recovery.
- Record
CVE-2021-20613- CVSS 3.1
- 7.5 High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H - CVSS 2.0
- 7.8 High
AV:N/AC:L/Au:N/C:N/I:N/A:C - Weakness
- CWE-665
- Updated
- 2026-11-02
CVE List No score
Improper initialization vulnerability in MELSEC-F series FX3U-ENET Firmware version 1.16 and prior, FX3U-ENET-L Firmware version 1.16 and prior and FX3U-ENET-P502 Firmware version 1.16 and prior allows a remote unauthenticated attacker to cause a denial-of-service (DoS) condition in communication function of the product by sending specially crafted packets. Control by MELSEC-F series PLC is not affected by this vulnerability, but system reset is required for recovery.
- Record
CVE-2021-20613- Updated
- 2026-11-02
EUVDEUVD-2021-8031 No score
Improper initialization vulnerability in MELSEC-F series FX3U-ENET Firmware version 1.16 and prior, FX3U-ENET-L Firmware version 1.16 and prior and FX3U-ENET-P502 Firmware version 1.16 and prior allows a remote unauthenticated attacker to cause a denial-of-service (DoS) condition in communication function of the product by sending specially crafted packets. Control by MELSEC-F series PLC is not affected by this vulnerability, but system reset is required for recovery.
- Record
EUVD-2021-8031- Updated
- 2026-11-03
GitHub AdvisoriesGHSA-4mv5-vjxv-hh3h No score
Improper initialization vulnerability in MELSEC-F series FX3U-ENET Firmware version 1.16 and...
Improper initialization vulnerability in MELSEC-F series FX3U-ENET Firmware version 1.16 and prior, FX3U-ENET-L Firmware version 1.16 and prior and FX3U-ENET-P502 Firmware version 1.16 and prior allows a remote unauthenticated attacker to cause a denial-of-service (DoS) condition in communication function of the product by sending specially crafted packets. Control by MELSEC-F series PLC is not affected by this vulnerability, but system reset is required for recovery.
- Record
GHSA-4mv5-vjxv-hh3h- Weakness
- CWE-665
- Updated
- 2026-11-02
Affected products
History
| Recorded | Changed | Sources |
|---|---|---|
| aliases | EUVD | |
| first indexed | CVE List, GitHub Advisories, NVD |
Dates are when Every CVE recorded each change. Upstream dates may differ.
In short
CVE-2021-20613 is a high vulnerability (CVSS 7.5) in Mitsubishielectric Fx3u-enet-l Firmware, published January 14, 2022. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 3.82%, the 90th percentile. No source names a fixed version.