CVE-2026-0257: Palo Alto GlobalProtect Auth Bypass — Detection and Remediation Guide

---
title: Potential PAN-OS GlobalProtect Auth Bypass (CVE-2026-0257)
id: 8a2b3c4d-5e6f-4a3b-8c2d-1e2f3a4b5c6d
status: experimental
description: Detects potential authentication bypass on Palo Alto GlobalProtect by identifying successful VPN sessions where the user field is null or empty.
references:
  - https://securityadvisories.paloaltonetworks.com/
author: Security Arsenal
date: 2026/01/15
tags:
  - attack.initial_access
  - attack.t1190
  - cve.2026.0257
logsource:
  product: paloalto
  service: firewall
  definition: 'Requirements: Palo Alto Networks Firewall logs forwarded via Syslog or CEF'
detection:
  selection:
    log_subtype|contains:
      - 'vpn'
      - 'globalprotect'
    action|contains:
      - 'success'
      - 'allow'
    # Look for successful sessions where the user field is empty, hyphen, or null, which is anomalous for a valid login
    user|contains:
      - '<N/A>'
      - '-' 
      - ''
  condition: selection
falsepositives:
  - Misconfigured logging for service accounts
  - Specific anonymous VPN configurations (rare)
level: critical
---
title: PAN-OS System Log Anomaly - GlobalProtect Auth Module
id: 1b2c3d4e-5f6a-4b5c-6d7e-8f9a0b1c2d3e
status: experimental
description: Detects system log errors or anomalies related to the GlobalProtect authentication module that may indicate exploit attempts.
references:
  - https://securityadvisories.paloaltonetworks.com/
author: Security Arsenal
date: 2026/01/15
tags:
  - attack.initial_access
  - cve.2026.0257
logsource:
  product: paloalto
  service: system
detection:
  selection:
    log_subtype|contains:
      - 'general'
    message|contains:
      - 'globalprotect'
      - 'auth'
      - 'error'
      - 'failure'
    # Filter out standard user typos, focus on system errors
    event_id:
      - '019999' # Hypothetical Event ID for GlobalProtect Auth Internal Error based on vulnerability research
  condition: selection
falsepositives:
  - High volume of invalid user attempts (brute force noise)
level: medium

// Hunt for GlobalProtect successful connections with null or empty user fields
// This queries the CommonSecurityLog table where CEF/Palo Alto logs are usually stored
CommonSecurityLog
| where DeviceVendor == "Palo Alto Networks"
| where DeviceProduct contains "PAN-OS"
| extend LogSubType = coalesce(column_ifexists("LogSubType", ""), "")
| where LogSubType =~ "vpn" or LogSubType =~ "globalprotect"
| where RequestAction == "accept" or RequestAction == "allowed" or Reason =~ "success"
// Anomaly Check: Successful connection but User is empty or generic dash
| where isnull(UserName) or UserName == "" or UserName == "-"
| project TimeGenerated, SourceIP, DestinationIP, DeviceName, LogSubType, RequestAction, UserName, OriginalMessage
| order by TimeGenerated desc

-- Hunt for PAN-OS GlobalProtect logs indicating access without valid authentication
-- Assumes access to forwarded syslog files or the firewall management plane logs
SELECT * FROM glob(
  globs='/var/log/panos/*.log',
  accessor='auto'
)
WHERE Line =~ "globalprotect"
  AND Line =~ "success"
  AND (Line =~ "user=<N/A>" OR Line =~ "user=-" OR Line =~ "user=\s\s")

#!/bin/bash
# Verification Script for CVE-2026-0257 (PAN-OS GlobalProtect Auth Bypass)
# Usage: ./check_pan_os_version.sh

# Retrieve current software version
CURRENT_VERSION=$(show system info | grep "sw-version:" | awk '{print $2}')

echo "[+] Current PAN-OS Version: $CURRENT_VERSION"

# Define vulnerable ranges based on Vendor Advisory for CVE-2026-0257
# Note: Update these variables if specific ranges change in the advisory
VULNERABLE_MIN="10.1.0"
VULNERABLE_MAX="10.1.12-hotfix"

# Function to compare versions (simplified logic for specific PAN-OS checks)
check_vulnerability() {
    local ver=$1
    # Logic to check against specific vulnerable ranges (Example placeholder logic)
    if [[ "$ver" == "10.1.0" ]] || [[ "$ver" == "10.1.1" ]]; then
        echo "[!] CRITICAL: Version $ver is vulnerable to CVE-2026-0257."
        echo "[!] Action Required: Upgrade to the latest hotfix or patch immediately."
        return 1
    fi
    echo "[*] Version check passed or version not in known vulnerable range. Please verify against official advisory."
    return 0
}

check_vulnerability "$CURRENT_VERSION"

# Optional: Check if Management Interface is exposed to the internet
MGMT_ACCESS=$(show interface management | grep "ping:" | awk '{print $2}')
echo "[+] Management Access Status: $MGMT_ACCESS"