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2023-06-13 08:00 (CEST)

Last update

2023-06-07 09:54 (CEST)




Article No° Product Name Affected Version(s)
1357872 FL MGUARD 2102 <= 10.1.1
1441187 FL MGUARD 4102 PCI <= 10.1.1
1357842 FL MGUARD 4102 PCIE <= 10.1.1
1357840 FL MGUARD 4302 <= 10.1.1
2702547 FL MGUARD CENTERPORT <= 8.9.0
2702820 FL MGUARD CENTERPORT VPN-1000 <= 8.9.0
2702884 FL MGUARD CORE TX <= 8.9.0
2702831 FL MGUARD CORE TX VPN <= 8.9.0
2700967 FL MGUARD DELTA TX/TX <= 8.9.0
2700968 FL MGUARD DELTA TX/TX VPN <= 8.9.0
2700197 FL MGUARD GT/GT <= 8.9.0
2700198 FL MGUARD GT/GT VPN <= 8.9.0
2701274 FL MGUARD PCI4000 <= 8.9.0
2701275 FL MGUARD PCI4000 VPN <= 8.9.0
2701277 FL MGUARD PCIE4000 <= 8.9.0
2701278 FL MGUARD PCIE4000 VPN <= 8.9.0
2702139 FL MGUARD RS2000 TX/TX-B <= 8.9.0
2700642 FL MGUARD RS2000 TX/TX VPN <= 8.9.0
2701875 FL MGUARD RS2005 TX VPN <= 8.9.0
2702470 FL MGUARD RS4000 TX/TX-M <= 8.9.0
2702259 FL MGUARD RS4000 TX/TX-P <= 8.9.0
2700634 FL MGUARD RS4000 TX/TX VPN <= 8.9.0
2200515 FL MGUARD RS4000 TX/TX VPN <= 8.9.0
2701876 FL MGUARD RS4004 TX/DTX <= 8.9.0
2701877 FL MGUARD RS4004 TX/DTX VPN <= 8.9.0
2700640 FL MGUARD SMART2 <= 8.9.0
2700639 FL MGUARD SMART2 VPN <= 8.9.0


The FL MGUARD family of devices is affected by two vulnerabilities.


Last Update
17. Mai 2023 08:24

A timing based side channel exists in the OpenSSL RSA Decryption implementation which could be sufficient to recover a plaintext across a network in a Bleichenbacher style attack. To achieve a successful decryption an attacker would have to be able to send a very large number of trial messages for decryption. The vulnerability affects all RSA padding modes: PKCS#1 v1.5, RSA-OEAP and RSASVE. For example, in a TLS connection, RSA is commonly used by a client to send an encrypted pre-master secret to the server. An attacker that had observed a genuine connection between a client and a server could use this flaw to send trial messages to the server and record the time taken to process them. After a sufficiently large number of messages the attacker could recover the pre-master secret used for the original connection and thus be able to decrypt the application data sent over that connection.

Last Update
7. Juni 2023 09:50
Improper Input Validation (CWE-20)

Improper Input Validation vulnerability in PHOENIX CONTACT FL/TC MGUARD Family in multiple versions may allow UDP packets to bypass the filter rules and access the solely connected device behind the MGUARD which can be used for flooding attacks.


CVE-2022-4304: The OpenSSL library contains a bug that leads to a timing oracle when RSA based ciphers are used without forward secrecy for network communication. By sending a very large number of trial messages, an attacker can try to achieve a decryption of encrypted network packets. This affects TLS connections to and from the FL MGUARD as well as VPN connections. The highest risk arises from deferred attempts to decrypt pre-recorded network sessions. The throttling feature of the FL MGUARD can impede but not prevent the attack.
There is a risk that attackers could decrypt network traffic encrypted by the FL MGUARD device.

CVE-2023-2673: If a FL MGUARD or TC MGUARD device is operated in static or autodetect stealth mode, UDP packets which are directed to the protected device do not pass the configured MAC filter rules. The issue does not compromise the incoming IPv4 packet filter, which blocks all incoming traffic by default. The issue does not affect multi stealth mode.
There is a risk that attackers could send UDP packets to the protected device which should have been filtered out.



  • Do not use RSA based ciphers for encryption of network traffic, use cipher suites with forward secrecy for TLS or IPsec communication and renew vulnerable certificates frequently.
  • Configure the incoming IPv4 packet filter carefully to protect clients from potentially malicious UDP packets.


The vulnerabilities are fixed in firmware versions 8.9.1 and 10.2.0. We strongly recommend all affected FL MGUARD users to upgrade to this or a later version.

Reported by

CVE-2022-4304: This vulnerability was discovered by Hubert Kario and Dmitry Belyavsky (Red Hat). We kindly appreciate the coordinated disclosure of this vulnerability by the finder.

CVE-2023-2673: This vulnerability was discovered internally.

PHOENIX CONTACT thanks CERT@VDE for the coordination and support with this publication.