CVE-2024-43391 Phoenix Contact: Firewall reconfiguration through the FW_PORTFORWARDING.SRC_IP in MGUARD devices

High 8.1 Published 10 Sep 2024 Updated 22 Aug 2025

A low-privileged remote attacker can modify firewall settings via an environment variable, leading to denial of service and security bypass on Phoenix Contact MGUARD devices.

Exploited in the wild: Not known
Login needed: Any signed-in user
Attackable: Over the internet
Victim action needed: Not needed
Fix: None listed

What is CVE-2024-43391?

CVE-2024-43391 is a high-severity vulnerability in PHOENIX CONTACT FL MGUARD 2102, published on 10 Sep 2024. Any signed-in user can exploit it over the network, with no action from the victim.

Official description

A low privileged remote attacker can perform configuration changes of the firewall services, including packet filter, packet forwarding, network access control or NAT through the FW_PORTFORWARDING.SRC_IP environment variable which can lead to a DoS.

Weakness: CWE-94

Which versions are affected by CVE-2024-43391?

It affects 36 products.

Products include Phoenixcontact Fl Mguard 2102 Firmware, Phoenixcontact Fl Mguard 2105 Firmware, Phoenixcontact Fl Mguard 4102 Pci Firmware, Phoenixcontact Fl Mguard 4102 Pcie Firmware, Phoenixcontact Fl Mguard 4302 Firmware, Phoenixcontact Fl Mguard 4305 Firmware and 30 more.

How do I fix CVE-2024-43391?

No fix has been published for CVE-2024-43391 yet. Limit exposure of the affected software until one is available.

Is CVE-2024-43391 being exploited?

There is no known exploitation of CVE-2024-43391 in the wild and no public exploit code.

Sources

Also known as GHSA-fqgj-hf47-9p78.