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Unit 42 threat brief artwork for the PHP2Shell vulnerabilities, showing a glowing network of red and blue lines over a world map.
Image: Palo Alto Networks Unit 42 (fair use).

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Palo Alto Networks Confirms Attackers Are Exploiting PHP2Shell Against Internet-Exposed PAN-OS Management Interfaces, as 19 of 20 Hotfixes Ship and One Remains Due October 30

The company's advisory now reports active exploitation against PAN-OS management interfaces reachable from the internet, days after Dream said a China-linked operator rooted 25 firewall servers with the same PHP flaws. Only the HTTPS web UI and XML API are affected, so cutting internet access to them is the fastest protection while hotfixes roll out.

Noah Park, ResponseNew York5 min read

NEW YORK - Palo Alto Networks now says attackers are exploiting the PHP2Shell flaws against its own firewalls. The company's security advisory for CVE-2026-109618 and CVE-2026-109619 states that "active exploitation has been observed targeting the Palo Alto Networks management interface exposed to the internet," confirming malicious use against PAN-OS that earlier versions of the advisory did not report.

The advisory gives no count of compromised devices, no attribution and no indicators. But it lands days after the Israeli security firm Dream reported that a China-linked operator had chained the same PHP flaws with the Fragnesia Linux kernel bug to root 25 firewall servers, then tunneled from a U.S. government-affiliated firewall into Active Directory. Dream did not name the firewall vendor, and Palo Alto Networks has not tied its exploitation notice to Dream's findings.

What is exposed, and what is not

PHP2Shell is a pair of remote code execution bugs in PHP's handling of out-of-memory and fatal errors. On PAN-OS, the advisory says, "This issue strictly affects the management web interface, which includes the HTTPS web UI and XML API service." A dataplane interface is affected only if a management profile is attached to it. GlobalProtect portals, gateways and Clientless VPN are not affected, and neither is Captive Portal. No special configuration is required to be vulnerable.

Header of the Palo Alto Networks security advisory for CVE-2026-109618, showing urgency Highest, severity 9.2 Critical and exploit maturity Attacked.
Image: Palo Alto Networks (fair use).The advisory header after the October 27 severity change.

That scoping is what makes the risk so uneven. Palo Alto Networks rates the flaw 9.2, critical, when the management interface is reachable from the internet, and raised the advisory to critical severity with its highest urgency on October 27. When access is restricted to a jump box that is the only system allowed to reach the management interface, the company's score drops to medium.

Nineteen of 20 hotfixes are out

The advisory lists 20 fixed builds across the PAN-OS 10.2, 11.1, 11.2, 12.1 and 12.2 trains. By its latest timeline entry, posted at 05:20 GMT on Thursday, all but one had shipped. The exception is 11.1.7-h12, still marked with an estimated date of October 30; customers on that branch can move to 11.1.16-h4 instead, according to the advisory's upgrade table. Older, unsupported PAN-OS versions need an upgrade to a supported fixed release.

Product status table from the Palo Alto Networks advisory listing the fixed PAN-OS builds for the 12.2, 12.1, 11.2, 11.1 and 10.2 trains, with 11.1.7-h12 still marked ETA 10/30, above the advisory's exploitation status line.
Image: Palo Alto Networks (fair use).Fixed PAN-OS builds as listed on October 29, and the advisory's exploitation status.

The same hotfix also covers a separate vulnerability in the brotli compression library used by Node.js, the company said, with one exception: 11.2.10-h16 includes only the PHP fixes, and 11.2.10-h17 includes both.

For teams that cannot patch immediately, the stopgaps come with conditions. Threat Prevention signatures, including Threat ID 543004 and a list of others in content versions 9162 through 9164 and later, protect the management interface only if inbound management traffic is routed through a dataplane port, the certificate for inbound management traffic is replaced, that traffic is decrypted so the firewall can inspect it, and threat prevention is enabled on it. Customers with Frontier Virtual Patching on PAN-OS 12.2.4 and later received Threat ID 543004 in advance, at 10:21 p.m. Pacific time on October 20.

What responders should do now

The first task is an exposure check, not a patch window. Confirm that no PAN-OS or Panorama management interface, and no dataplane interface with a management profile attached, answers from the internet, and limit management access to trusted internal addresses as the advisory recommends. Then apply the fixed build for each train.

Any firewall whose management interface was reachable from the internet while unpatched should be handled as a possible compromise rather than a patching task: review administrator sessions, configuration commits and XML API activity since October 21, when the advisory was first published. The Dream case, in which the intruder moved from a firewall into Active Directory and extracted credentials, is the reason to also review the directory accounts a firewall holds, such as service accounts used for user identification, and to look for logons by those accounts from unexpected hosts.

Excerpt of the Unit 42 PHP2Shell threat brief stating that Cortex Xpanse identified more than 22.6 million exposed instances potentially vulnerable to the two CVEs.
Image: Palo Alto Networks Unit 42 (fair use).Unit 42's exposure estimate covers PHP deployments broadly, not only firewalls.

PHP2Shell reaches far beyond firewalls. Palo Alto Networks' Unit 42 said its Cortex Xpanse telemetry found more than 22.6 million exposed instances potentially vulnerable to the two CVEs, and its threat brief publishes an XQL hunting query for post-exploitation commands launched by PHP web server and worker processes.

Sources:


Noah Park covers incident response and blue-team operations for SOCtember from New York.

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