Palo Alto PAN-OS Flaw Under Active Exploitation Enables Remote Code Execution

Summary

Palo Alto Networks disclosed CVE-2026-0300, a critical buffer overflow in PAN-OS User-ID Authentication Portal affecting PA-Series and VM-Series firewalls. The vulnerability (CVSS 9.3) enables unauthenticated remote code execution with root privileges and is actively being exploited in limited cases, particularly when the portal is internet-facing. Patches are scheduled for May 13, 2026, with interim mitigation requiring portal access restriction to trusted networks or complete disablement.

Full text

Palo Alto PAN-OS Flaw Under Active Exploitation Enables Remote Code Execution Ravie LakshmananMay 06, 2026Vulnerability / Network Security Palo Alto Networks has released an advisory warning that a critical buffer overflow vulnerability in its PAN-OS software has been exploited in the wild. The vulnerability, tracked as CVE-2026-0300, has been described as a case of unauthenticated remote code execution. It carries a CVSS score of 9.3 if the User-ID Authentication Portal is configured to enable access from the internet or any untrusted network. The severity comes down to 8.7 if access to the portal is restricted to only trusted internal IP addresses. "A buffer overflow vulnerability in the User-ID Authentication Portal (aka Captive Portal) service of Palo Alto Networks PAN-OS software allows an unauthenticated attacker to execute arbitrary code with root privileges on the PA-Series and VM-Series firewalls by sending specially crafted packets," the company said. According to Palo Alto Networks, the vulnerability has come under "limited exploitation," specifically targeting instances where the User-ID Authentication Portal has been left publicly accessible. The following versions are impacted by the flaw - PAN-OS 12.1 - < 12.1.4-h5, < 12.1.7 PAN-OS 11.2 - < 11.2.4-h17, < 11.2.7-h13, < 11.2.10-h6, < 11.2.12 PAN-OS 11.1 - < 11.1.4-h33, < 11.1.6-h32, < 11.1.7-h6, < 11.1.10-h25, < 11.1.13-h5, < 11.1.15 PAN-OS 10.2 - < 10.2.7-h34, < 10.2.10-h36, < 10.2.13-h21, < 10.2.16-h7, < 10.2.18-h6 The issue, as it stands, is unpatched, with Palo Alto Networks planning to release fixes starting May 13, 2026. The company also said the vulnerability is applicable only to PA-Series and VM-Series firewalls that are configured to use the User-ID Authentication Portal. "Customers following standard security best practices, such as restricting sensitive portals to trusted internal networks are at a greatly reduced risk," it added. In the absence of a patch, users are advised to either restrict User-ID Authentication Portal access to only trusted zones, or disable it entirely, if it's not required. Found this article interesting? Follow us on Google News, Twitter and LinkedIn to read more exclusive content we post. SHARE     Tweet Share Share Share SHARE  cybersecurity, Firewall, network security, Palo Alto Networks, remote code execution, Threat Intelligence, Vulnerability, zero day ⚡ Top Stories This Week Harvester Deploys Linux GoGra Backdoor in South Asia Using Microsoft Graph API Malicious KICS Docker Images and VS Code Extensions Hit Checkmarx Supply Chain Apple Fixes iOS Flaw That Let FBI Recover Deleted Signal Messages Vercel Finds More Compromised Accounts in Context.ai-Linked Breach ThreatsDay Bulletin: $290M DeFi Hack, macOS LotL Abuse, ProxySmart SIM Farms +25 New Stories Bitwarden CLI Compromised in Ongoing Checkmarx Supply Chain Campaign LMDeploy CVE-2026-33626 Flaw Exploited Within 13 Hours of Disclosure FIRESTARTER Backdoor Hit Federal Cisco Firepower Device, Survives Security Patches Researchers Uncover Pre-Stuxnet ‘fast16’ Malware Targeting Engineering Software ⚡ Weekly Recap: Fast16 Malware, XChat Launch, Federal Backdoor, AI Employee Tracking and More Checkmarx Confirms GitHub Repository Data Posted on Dark Web After March 23 Attack Microsoft Confirms Active Exploitation of Windows Shell CVE-2026-32202 Chinese Silk Typhoon Hacker Extradited to U.S. Over COVID Research Cyberattacks Microsoft Patches Entra ID Role Flaw That Enabled Service Principal Takeover Researchers Discover Critical GitHub CVE-2026-3854 RCE Flaw Exploitable via Single Git Push Critical cPanel Authentication Vulnerability Identified — Update Your Server Immediately ⭐ Featured Resources [Webinar] Stop Chasing Alerts and Start Focusing on Real Exposures [Guide] How to Enable Secure Data Movement Without Added Risk Learn How Hidden Identity Blind Spots Weaken Your Security Systems [Guide] Learn a Practical Framework to Evaluate AI Tools for Production

Indicators of Compromise

• cve — CVE-2026-0300

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