CVE-2026-0227 Critical DOS Vulnerability Palo Alto Networks PAN-OS

Jan 17

BLUF

A high-severity Denial of Service (DoS) vulnerability in PAN-OS allows unauthenticated attackers to disable firewall protection.

Executive Cost Summary

This cost analysis was developed by the CyberDax team using expert judgment and assisted analytical tools to support clarity and consistency.

For organizations affected by unauthenticated denial-of-service attacks against Palo Alto Networks PAN-OS firewalls leveraging CVE-2026-0227, the primary financial exposure stems from operational disruption, emergency response labor, and downstream business interruption rather than data loss or theft.

Estimated Total Cost Ranges (Mid-size to Large Organization)

· Low-end total cost: $150,000 – $350,000

o (single firewall outage, rapid recovery, limited business disruption)

· Typical expected range: $400,000 – $1.2M

o (multi-hour outage, workforce disruption, coordinated response effort)

· Upper-bound realistic scenarios: $1.5M – $3.5M

o (repeated exploitation, extended downtime, customer-facing service impact)

Key Cost Drivers

· Duration and frequency of firewall downtime

· Percentage of workforce or customers dependent on GlobalProtect connectivity

· Need for after-hours or third-party incident response support

· Revenue dependency on always-on digital or remote-access services

· Strength of redundancy and failover architecture

Targeted Sectors

· All Palo Alto Networks Firewall users

Countries

· Global

Date of First Reported Activity

· Jan 15, 2026

Date of Last Reported Activity Update

· Jan 16, 2026

CVE-2026-0227

(CVSS 8.6 - High). Affects PAN-OS 10.1 and later when GlobalProtect is enabled.

CVS:3.1

· (7.5) AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

CVSS:4.0

· (6.6)AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:U/AU:Y/R:U/V:D/RE:M/U:Amber

Nessus ID

· 290249

Is CVE-2026-0227 on the KEV list?

· Not at this time

What is the CISA patch by date?

· Not applicable at this time

Link to patching information

· hxxps://security.paloaltonetworks.com/CVE-2025-4620

Malware name:

· Not applicable at this time.

Malware sample

· Not applicable at this time

IOCs

Due to the nature of the vulnerability (unauthenticated network requests), organizations can identify exploitation attempts through the following artifacts:

· Log Artifacts

o Monitor for repeated authd or gpsvc process restarts in system logs. A key indicator is the firewall transitioning to "maintenance mode" after multiple failed service restarts.

· Network Patterns

o Look for unauthenticated, malformed HTTPS requests specifically targeting the GlobalProtect interface (/global-protect/). Exploitation involves "repeated attempts" or specific request sequences designed to trigger resource handling errors.

· Scanning Activity

o Security researchers have noted increased scanning activity targeting exposed GlobalProtect gateways specifically for this flaw.

· Availability Alerts

o Frequent, unexplained downtime of the Data Plane while the Management Plane remains partially accessible (but in restricted recovery mode) is a primary symptom of successful exploitation.

TTPs

· T1499 Endpoint Denial of Service

· T1499.004 Service Stop

o Repeated exploitation forces the firewall into maintenance mode, requiring manual intervention to restore services

Suggested rules / potential hunts

Suricata

Look for repeated, rapid-fire sessions to /global-protect/ or /php/ endpoints on GlobalProtect ports (typically 443) that lack typical authentication headers.

alert http $EXTERNAL_NET any -> $HOME_NET [443] (msg:"ET EXPLOIT Possible Palo Alto GlobalProtect DoS Attempt (CVE-2026-0227)"; flow:established,to_server; content:"/global-protect/"; http_uri; threshold:type threshold, track by_src, count 20, seconds 60; reference:cve,2026-0227; classtype:attempted-dos; sid:10002026; rev:1;)

SentinelOne

Hunt for a spike in agents losing connection to specific external IP ranges.

EndpointType = "Laptop", "Desktop" AND NetConnDirection = "Outbound" AND NetConnAddress IN [Your_GlobalProtect_IPs] AND EventType = "Network Connection Failed"

Hunt for suspicious process executions on sensitive endpoints that occurred during a known firewall downtime.

ProcessName NOT IN ["trusted_app.exe"] AND (IndicatorName = "Unsigned Executable" OR IndicatorName = "Abnormal Process Tree")

Monitor for the PanGPS.exe process (GlobalProtect agent) failing or reporting unusual connection errors on the endpoint side.

ProcessName = "PanGPS.exe" AND (IndicatorName = "Process Crash" OR EventType = "Process Terminated")

Splunk

Look for frequent "maintenance mode" triggers or critical system errors.

index=pan_logs sourcetype="pan:system" (eventid="maint-mode" OR "maintenance mode")

| stats count, earliest(_time) as first_seen, latest(_time) as last_seen by device_name

| where count > 1

Identify unauthenticated remote IPs sending abnormal packet types to the GlobalProtect portal.

index=pan_logs sourcetype="pan:traffic" app="global-protect" action="allow"

| stats count by src_ip

| eventstats avg(count) as avg_conn, stdev(count) as std_conn

| where count > (avg_conn + 3*std_conn)

Delivery Method

· Network based attack

Email sample

· Not applicable

References

Tenable

· hxxps://www.tenable.com/cve/CVE-2026-0227/plugins

Security Palo Alto Networks