After informing customers that it’s investigating claims of a new firewall remote code execution vulnerability, Palo Alto Networks on Friday confirmed that a new zero-day is being exploited in attacks.

The cybersecurity giant published an advisory on November 8, urging customers to ensure that access to the PAN-OS management interface is secured, in light of claims about a remote code execution vulnerability.

Palo Alto Networks initially said it had not seen any indication of a zero-day being exploited, but on Friday it updated its advisory to say that it “has observed threat activity exploiting an unauthenticated remote command execution vulnerability against a limited number of firewall management interfaces which are exposed to the Internet”.

It’s still unclear how the vulnerability came to light, who has exploited it, and who has been targeted in the attacks.

A CVE identifier has yet to be assigned to the vulnerability, but it has a CVSS score of 9.3, which puts it in the ‘critical severity’ category. 

Palo Alto told customers that it’s working on patches and threat prevention signatures, which it hopes to release soon. 

In the meantime, customers have been advised to ensure that access to the firewall management interface is possible only from trusted IP addresses and not from the internet. 

“The vast majority of firewalls already follow this Palo Alto Networks and industry best practice,” Palo Alto Networks said.

The security firm noted, “If the management interface access is restricted to IPs the risk of exploitation is greatly limited, as any potential attack would first require privileged access to those IPs.”

The company believes that Prisma Access and Cloud NGFW products are not affected. 

This is not the only Palo Alto product vulnerability whose exploitation has come to light in recent days. The US cybersecurity agency CISA said it’s aware of three vulnerabilities impacting Palo Alto Networks Expedition that have been exploited in the wild. 

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